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  • 451.
    Viklund, Peter
    et al.
    RISE, Swerea, Swerea KIMAB.
    Pettersson, Rachel
    RISE, Swerea, Swerea KIMAB.
    The effect of a sulphur-containing additive on the initial corrosion of superheater tubes in a waste-fired boiler2008In: EUROCORR 2008 - European Corrosion Congress: Managing Corrosion for Sustainability, Book of Abstracts, 2008, p. 164-Conference paper (Refereed)
    Abstract [en]

    The major drawback to generating electricity from waste-fired boilers is the rapid corrosion of superheaters which increases the maintenance costs. Within the last few years it has been shown that additions of ammonium sulphate to biomass-fired boilers decrease the corrosion tendencies. This paper reports on the effects of ammonium sulphate on corrosion in a waste-fired CFB boiler. Internally cooled probes were exposed at a position corresponding to the one of superheater tubes. The probe temperature was 500°C, simulating a steam temperature of about 450°C. Both the austenitic steel EN 1.4301 (Fe-18Cr-9Ni) and the low-alloyed ferritic steel EN 1.7380 (Fe-2.25Cr-1Mo) were tested. During exposure the concentration of alkali chlorides in the flue gas was measured and a decrease was observed when adding ammonium sulphate. After 4 hours of exposure, the probes were removed for detailed analysis with SEM-EDX, TOF-SIMS and XRD. The sides of the tubes facing the flue gas were covered with a calcium-rich deposit, while sodium and potassium were the main components on the lee side. The results also show that ammonium sulphate shifted the deposit composition from chioride-rich and highly corrosive, to one significantly less corrosive and dominated by sulphates of Na, K and Ca. Metallography shows a marked difference in corrosion attack between the two steels. Iron chlorides accumulate at the metal/oxide interface of the ferritic steel, while the amounts of iron chlorides were significantly lower in the austenitic steel. These results indicate that ammonium sulphate has the potential to reduce corrosion in waste-fired boilers and that austenitic stainless steels are more likely to resist corrosion in these environments than low alloy ferritic steels.

  • 452.
    Vinka, Tor-Gunnar
    RISE, Swerea, Swerea KIMAB.
    Katodiskt skydd av stålkonstruktioner i vatten och jord2014Report (Refereed)
    Abstract [sv]

    Katodiskt skydd är en elektrokemisk skyddsmetod, som används på metallkonstruktioner i vatten, jord och betong samt i vissa aggressiva vätskor inom bland annat cellulosaindustrin och den kemiska industrin. I rapporten beskrivs inledningsvis principen och funktionen för katodiskt skydd. Utformningen av katodiskt skydd med offeranoder och påtryckt ström beskrivs noggrant. Vid katodiskt skydd med offeranod ansluts skyddsföremålet till en mera ”oädel” metall Som offeranoder används magnesium-, zink- eller aluminiumlegeringar. Olika materialsammansättningar, användningsområden och elektrokemiska egenskaper som elektrodpotential, strömkapacitet och anodförbrukning tas upp för offeranoder. Vid katodiskt skydd med påtryckt ström används en yttre strömkälla, likriktarenhet, och strömmatade anoder, som bör vara av så kallad olöslig typ till exempel anoder av ädelmetallbelagt titan (MMO-anoder). De strömmatade anoderna kopplas till pluspolen på likriktarenheten och skyddsföremålet till minuspolen. Olika sorters anodmaterial, användningsområden och elektrokemiska egenskaper som maximal strömbelastning och anodförbrukning tas upp för strömmatade anoder. Olika skyddskriterier för katodiskt skydd, främst skyddspotential men också andra skyddskriterier som potentialförskjutning och potentialavklingning redovisas ingående. Mätning av skyddspotential inklusive felkällor vid mätning och strömbehov för katodiskt skydd i olika miljöer med olika sorters skyddsbeläggning diskuteras också i rapporten. I avsnittet om kombinationen katodiskt skydd och målning tas det upp vilka målningssystem som kan kombineras med katodiskt skydd främst med tanke på risken för katodisk vidhäftningsförlust. Vid användning av katodiskt skydd finns risk att närbelägna metallkonstruktioner utsätts för skadlig sekundärverkan. Med sekundärverkan avses ökning av korrosionshastigheten för en metallkonstruktion på grund av läckström från det katodiska skyddet. Vid sekundärverkan ”läcker” en del av skyddsströmmen in i den främmande konstruktionen och orsakar läckströmskorrosion vid utträdet ur konstruktionen. Riskerna för sekundärverkan diskuteras ingående i rapporten. På slutet av rapporten tas standardisering om katodiskt skydd upp och kommenteras. I det sista avsnittet i rapporten finns en kommenterad litteraturlista med förslag på litteratur på svenska, engelska och tyska.

  • 453.
    Vinka, Tor-Gunnar
    RISE, Swerea, Swerea KIMAB.
    Korrosion i bräckt vatten2014Report (Refereed)
    Abstract [en]

    Med bräckt vatten menas vatten med en salthalt mellan 0,25 – 1 %. Vatten med salthalt över 1 % kallas saltvatten alternativt havsvatten. Många undersökningar av korrosion i havsvatten finns redovisade i litteraturen. Däremot är undersökningar utförda i bräckt vatten kraftigt begränsade. Korrosionen i bräckt vatten är alltså dåligt undersökt. Det finns få publicerade undersökningar och därmed få korrosionshastigheter för Bottenviken, Bottenhavet och Östersjön. Alla här redovisade undersökningar behandlar enbart stålspontskajer av kolstål. Undersökningarna har oftast fokuserats på att finna den maximala korrosionen på stålsponten. Den maximala korrosionshastigheten står oftast att finna i skvalpvattenzonen. Däremot finns få korrosionshastigheter för undervattenszonen. Korrosionen i undervattenszonen bestämts i första hand av vattnets egenskaper. Korrosionen i skvalpvattenzonen beror till stor del av vattenståndet och vindförhållandena på exponeringsplatsen, men också av vattnets egenskaper som till exempel salthalten. Från litteraturgenomgången framgår att korrosionen i undervattenszonen i bräckt vatten ligger mellan korrosionen i sötvatten och den i havsvatten. Vid dimensionering av konstruktioner i vatten mot korrosion använts ofta korrosionshastigheterna 50 µm/år i sötvatten och 100 µm/år i havsvatten för kolstål i undervattenszonen. Ett lämpligt värde för kolstål i undervattenszonen i bräckt vatten torde vara 70 µm/år Det krävs ett exponeringsprogram för att säkrare bestämma korrosionshastigheten för kolstål i bräckt vatten. Om andra metaller än kolstål skall användas i bräckt vatten är ett exponeringsprogram nödvändigt för få fram korrosionsegenskaperna.

  • 454.
    Vinka, Tor-Gunnar
    RISE, Swerea, Swerea KIMAB.
    Korrosion på kolstål och zink i moränjord2014Report (Refereed)
    Abstract [sv]

    Morän är den dominerande jordarten i Sverige, ca 75 % av markytan täcks av morän. Den totala moränarean är än större, ca 95 %, eftersom moränen överlagras av yngre jordlager i områden som täcktes av hav eller isdämda sjöar efter den sista nedisningen. Moränen är en glacial jordart som avsatts av inlandsisen eller dess smältvatten. Inlandsisen bröt loss eller slipade bort material från berggrunden. Materialet från berggrunden krossades och blandades med äldre jordarter och detta material avsattes som en osorterad jordart. Provplåtar av kolstål och zink exponerades på två provningsplatser. I Munkarp (Höörs kommun, Skåne län) exponerades provplåtar i likartade jordar med olika trädslag – björk, bok och gran. Dessa trädslag ger upphov till viss skillnad i försurningshänseende. Vid provningsplatsen i Stråsan (Falu kommun, Dalarnas län) exponerades provplåtar dels i kvävegödslad jord, dels på kontrollyta utan gödsling. Korrosionshastigheten var betydligt högre för kolstål och zink i kvävegödslad jord än i intilliggande ogödslad jord i Stråsan. Den kvävegödslade jorden var också betydligt mera försurad än jorden på den ogödslade kontrollytan. Korrosionshastigheten var för kolstål högre i jord med granbestånd, som var mest försurad, än i intilliggande jordar med björk respektive bokbestånd i Munkarp. Den lägsta korrosionshastigheten uppmättes på den ogödslade kontrollytan i Stråsan. Korrosionshastigheten för kolstål avtog generellt med exponeringstiden. Den lokala korrosionshastigheten var högre på den gödslade ytan än på övriga provningsplatser och den avtog generellt med exponeringstiden. Den lokala korrosionshastigheten för varmvalsat kolstål i morän var högre än eller åtminstone lika hög som de högsta uppmätta lokala korrosionshastigheterna på provplåtar av varmvalsat kolstål i olika svenska jordarter. Den höga lokala korrosionshastigheten på främst kolstål beror troligen på förekomsten av mikro- och miniluftningsceller på metallytan. Dessa luftningsceller torde uppstå på grund av den stora lokala heterogeniteten i jorden. Korrosionshastigheten var över lag låg för zink och ungefär lika stor i de undersökta moränerna med undantag för den kvävegödslade moränen i Stråsan där korrosionshastigheten var betydligt högre, 7 µm/år. Korrosionshastigheten för zink avtog generellt med exponeringstiden. Den lokala korrosionshastigheten var ungefär lika stor på alla provningsplatser och den avtog generellt med exponeringstiden. Den låga korrosionshastigheten hos zink i Munkarp och på kontrollytan i Stråsan beror på att zinken passiverats genom utfällning av zinkhydroxidkarbonatet hydrozinkit på zinkytan.

  • 455.
    Vinka, Tor-Gunnar
    RISE, Swerea, Swerea KIMAB.
    Reparation av skador i förzinkningsskikt2014Report (Refereed)
    Abstract [sv]

    Skador på varmförzinkningsskiktet kan uppdelas i skador i anslutning till varmförzinkning och skador vid transport, lagring och montering av varmförzinkat gods. Exempel på skador i förzinkningsskiktet i anslutning till varmförzinkning: Fläckar utan zinkskikt (”svarta fläckar”), skador i anslutning till upphängning av godset och skador vid efterbearbetning av det varmförzinkade godset. Fläckar utan zinkskikt uppstår då stålets yta inte väts av zinksmältan. Någon zinkbeläggning bildas då inte på stålytan. Fläckarna uppstår då stålytan inte är ren. Glödskalsrester, svetsslagg, oljor, fetter och färger är exempel på föroreningar av stålytan. Ett större problem är dock skador på förzinkningsskiktet vid transport, lagring och montering av varmförzinkat gods. Skador med avflagning av zinkskikt orsakas ofta av stötar och friktion mellan olika godsdelar vid transport och lagring. Det är därför viktigt att packetera godset på ett bra sätt för att undvika skador. Lagning av uppkomna skador på förzinkningszinket kan ske på olika sätt: Målning med zinkrik färg, bättring med lågsmältande lödzink och sprutförzinkning (termisk sprutning). Målning med zinkrik färg den vanligaste reparationsmetoden. Vid målning med zinkrik färg används färg med minst 92 mass-% zink (Zn) i det torra färgskiktet. Målning med zinkrik färg brukar ofta kallas för kallgalvanisering. Det finns en felaktig tro att zinken i den zinkrika färgen ”bränner” ihop med stålet vid kallgalvanisering. Kallgalvanisering är emellertid ett målningsförfarande av det enklare slaget och inget metallbeläggningsförfarande. Det är endast vid varmförzinkning som man får en metallurgisk bindning mellan stål och zink. Vid andra lagningsmetoder än varmförzinkning fås mekanisk bindning och ingen metallurgisk bindning mellan beläggningen och stålet. Det är mycket viktigt att skikttjockleken blir tillräckligt tjock. Skikttjockleken på reparerade områden bör vara minst 100 µm om inte annat överenskommits mellan köpare och varmförzinkare. Vid reparation av skador i varmförzinkningsskiktet gäller att den största totala arean hos skadade ytor får vara 0,5 % av hela godsytan som varmförzinkats och att den största individuella skadan vara högst 10 cm2. Med sprutförzinkning menas termisk sprutning av smält zink med en sprutpistol. Smält zink i form av droppar slungas mot stålytan med hjälp av tryckluft. Vid sprutförzinkning är rengöringen av skadestället viktigt. Skadestället måste blästras. Sprutförzinkning är inte lämpligt för reparation av mindre skador eftersom blästringen avverkar ett större område än skadestället. Vid bättring med lödzink påföres lödzinken företrädesvis på varmt gods direkt vid zinkbadet eller uppvärmes vid påföring. Skadeytan slipas försiktigt ren. Det vanligaste sättet att laga skador i förzinkningsskiktet är målning med zinkrik färg. Reparation av varmförzinkningsskikt fungerar inte alltid i praktiken. Olika orsaker kan vara: dålig förbehandling, för tunt färgskikt, ingen täckfärg används och lagning av för stora skador i förzinkningsskiktet. Det är mycket viktigt att skikttjockleken blir tillräckligt stor. Skikttjockleken på reparerade områden bör vara minst 100 µm. Påföring av zinkrik färg från sprayburk är olämpligt eftersom zinkskiktet blir alltför tunt. Skikttjockleken hos färgskiktet (torrt färgskikt) blir inte mer än cirka 20 µm vid användning av zinkrik färg från sprayburk. Täckfärgen behövs för att bygga upp ett tillräckligt tjockt lagningsskikt och skydda den zinkrika färgen mot blåsbildning. I vatten och jord finns risk för blåsbildning hos den zinkrika grundfärgen.

  • 456.
    Vinka, Tor-Gunnar
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Tidblad, Johan
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Korrosion på metaller i kloridhaltig atmosfär på Bohus-Malmön2013Report (Refereed)
    Abstract [sv]

    Rapporten redogör för en exponering under ett år av två olika provtagare för mätning av kloriddeponering och metaller på Bohus-Malmön under perioden 2008-2009. Syftet med exponeringen var att jämföra de två metoderna för kloriddeponering och föreslå den mest lämpliga för framtida mätningar och ta fram systematiska data för korrosion av olika bruksmetaller på platser på Bohus-Malmön med varierande kloridhalt och avstånd från havet. De två metoder som använts för kloriddeponering är ”wet candle”, bestående av en veke med strumpa i kontakt med en lösning av glycerol, samt en provtagare bestående av ett teflonfilter rullat kring en cylinder. Den stora skillnaden mellan de båda metoderna är att ”wet candle” hela tiden är våt medan den passiva provtagaren kan vara torr eller våt, beroende på den omgivande luftens fuktighet. Månadsvisa mätningar har genomförts på tre olika platser på Bohus-Malmön med ett avstånd från havet mellan 50 och 350 m. Båda metoderna och alla tre mätplatserna, totalt sex mätserier visar i stort sett samma årstidsvariation. Den största deponeringen skedde under augusti - oktober och dessa tre månader stod tillsammans för 60 % av den totala kloriddeponeringen. Totalt sett ger dock teflonfiltret systematiskt låga värden på kloriddeponering och kan inte ersätta wet candle i den nuvarande utformningen. Det systematiska felet kan bero på mindre deponering på teflonfiltret, eftersom detta inte alltid är fuktigt, eller på att tidigare deponerad klorid blåses bort av starka vindar. Systematiska data för korrosion av kolstål, koppar, zink, förzinkat stål, och tre olika aluminiumsorter har uppmätts på fem olika platser på Bohus-Malmön med varierande kloridhalt och avstånd från havet. Databasen kan användas för att undersöka inverkan av avstånd från havet samt för att jämföra olika materials känslighet för kloriddeponering. Kloriddeponeringen har det starkaste sambandet med avstånd från havet, varje 100 m i ökat avstånd från havet resulterar i en ungefärlig halvering av kloriddeponeringen. För korrosionen är sambandet betydligt svagare men tydligast för kolstål, koppar och aluminium Al 1050A, följt av zink och Al 3003 och sist förzinkat stål och Al 6063 som praktiskt taget har ingen avklingning alls med avstånd från havet. Uppmätta korrosionshastigheterna för kolstål, zink, koppar och aluminium för första året exponering har jämförts med beräknade korrosionshastigheter med ekvationer i svensk standard SS-EN ISO 9223:2012. De beräknade korrosionshastigheterna var högre än de uppmätta förutom för koppar där uppmätt korrosionshastighet var högre än den beräknade närmast havet.

  • 457.
    Vittonato, J.
    et al.
    TOTAL, France.
    Diler, Erwan
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Larché, Nicolas
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Castillon, F.
    Terega, France.
    High sensitive sensors for collection of cathodic polarization data and determination of protection potential criteria of buried structures2019In: NACE - International Corrosion Conference SeriesVolume 2019-March, 2019, Article number 13337Corrosion Conference and Expo 2019; Nashville; United States; 24 March 2019 through 28 March 2019;, National Assoc. of Corrosion Engineers International , 2019Conference paper (Refereed)
    Abstract [en]

    The installation of metallic coupons in the vicinity of buried pipes under cathodic protection (CP) allows theoretically to measure the potential and the current density through the simulated coating defect. Nevertheless, this type of monitored coupon does not provide direct information on the actual efficiency of the CP and corrosion rates that could be caused by a CP failure over time or not adapted CP design. According to the soil resistivity and the corrosion potential in absence of CP, a protection potential is generally targeted following the standard recommendations. However, the soil resistivity as well as the corrosion potential might depend on the seasonal fluctuations and the protection potential might vary as function of the considered standard. Moreover, all soils parameters cannot be considered in recommendations from standards and cathodic protection criteria can be sometimes debatable. In this study, very sensitive electrical resistance (ER) sensors, used for obtaining precise corrosion data in real-time, were adapted for soil applications. They were used in the selected soils and conditions to determine the off potential and current density corresponding to a corrosion rate of 10 µm/year, which corresponds to the maximal corrosion rate of buried structures considered as protected according the standard ISO 15589-1:2015. The adapted ER sensors appeared to be particularly suitable for determining the protection potential and CP criteria in a relatively short time. For the tested soils and conditions, the results showed that the cathodic protection criteria recommended in ISO 15589-1: 2015 are conservative compared to those measured experimentally. This method therefore seems particularly relevant for the determination of the protection potential in complex or polluted media, in the absence of data in the literature.

  • 458.
    Vucko, Flavien
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Thierry, Dominique
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Weber, Bastien
    ArcelorMittal, France.
    Luckeneder, Gerald
    Voestalpine Stahl GmbH, Austria.
    Bschorr, Thomas
    Gesellschaft für Schweisstechnik International GmbH, Germany.
    Rother, Klemens
    University of Applied Science, Germany.
    Sciaboni, Crstiano
    Centro Sviluppo Materiali SpA, Italy.
    Sczepanski, Julian
    Bayerische Motoren Werke AG, Germany.
    Simultaneous & alternated fatigue-corrosion performance of joined materials for automotive applications2015In: European Corrosion Congress, EUROCORR 2015, Austrian Society for Metallurgy and Materials (ASMET) , 2015Conference paper (Refereed)
  • 459.
    Watt, J.
    et al.
    Middlesex University.
    Tidblad, Johan
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Hamilton, R.
    Middlesex University.
    Kucera, Vladimir
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    The effects of air pollution on cultural heritage2009Book (Refereed)
  • 460.
    Weber, C.
    et al.
    Lund University.
    Fuhrer, A.
    Lund University.
    Fasth, C.
    Lund University.
    Lindwall, Greta
    RISE, Swerea, Swerea KIMAB.
    Samuelson, L.
    Lund University.
    Wacker, A.
    Lund University.
    Probing confined phonon modes by transport through a nanowire double quantum dot2010In: Physical Review Letters, ISSN 0031-9007, E-ISSN 1079-7114, Vol. 104, no 3Article in journal (Refereed)
    Abstract [en]

    Strong radial confinement in semiconductor nanowires leads to modified electronic and phononic energy spectra. We analyze the current response to the interplay between quantum confinement effects of the electron and phonon systems in a gate-defined double quantum dot in a semiconductor nanowire. We show that current spectroscopy of inelastic transitions between the two quantum dots can be used as an experimental probe of the confined phonon environment. The resulting discrete peak structure in the measurements is explained by theoretical modeling of the confined phonon mode spectrum, where the piezoelectric coupling is of crucial importance. © 2010 The American Physical Society.

  • 461.
    Weber, C.
    et al.
    Lund University.
    Lindwall, Greta
    RISE, Swerea, Swerea KIMAB.
    Wacker, A.
    Lund University.
    Zero-phonon line broadening and satellite peaks in nanowire quantum dots: The role of piezoelectric coupling2009In: Physica status solidi. B, Basic research, ISSN 0370-1972, E-ISSN 1521-3951, Vol. 246, no 2, p. 337-341Article in journal (Refereed)
    Abstract [en]

    We investigate the influence of the one-dimensional character of the phonon modes in a catalytically grown GaAs nanowire on the absorption spectrum of an embedded quantum dot, focusing on the contribution from the piezoelectric coupling. In general, the reduced dimensionality of the phonons leads to spectral side peaks and a zero-phonon line broadening due to the energetically lowest (acoustic) phonon mode. While the deformation potential predominantly couples to radial modes, the piezoelectric interaction can also couple strongly to modes of axial character, leading to additional absorption features. The contribution of the piezoelectric coupling to the zero-phonon line is negligible. © 2009 WILEY-VCH Verlag GmbH & Co. KGaA.

  • 462.
    Werke, Mats
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Kristoffersen, Hans
    RISE - Research Institutes of Sweden, Materials and Production, IVF.
    Haglund, S.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Svensson, L.
    Bharat Forge Kilsta AB.
    Nord, A.
    Bharat Forge Kilsta AB.
    Predicting residual stresses and hardness of a critical component using a combination of numerical and empirical methods2008In: Steel Research International, Wiley-VCH Verlag , 2008, Vol. 79, no 2, p. 812-819Conference paper (Refereed)
    Abstract [en]

    This paper describes the experiences gained when using numerical and empirical methods in order to predict the accumulated surface characteristics for a safety component after several forging steps, controlled cooling and blasting. The forging steps were simulated in a sequence using one Finite Element (FE) code. The output forging mesh was used as input to the cooling simulation but was too coarse in order to reflect surface characteristics. The decarburisation effect during cooling that may influence the surface characteristics was not included in the cooling model. An attempt to create a parametric model of the blasting machine with output residual stresses and hardness as a function of input residual stresses, hardness and process parameters indicated the need of further investigation concerning the physical phenomena during blasting in the machine. A new method was developed for analysing the influence of the blasted surface texture on the stress intensity. The measured residual stresses and hardness span caused by variations in the blasting process were successfully used together with the stress intensity factor as input to a fatigue strength analysis. In order to establish a seamless chain of models through the manufacturing sequence further development concerning cooling and blasting models is required. © 2008 Verlag Stahleisen GmbH, Düsseldorf.

  • 463.
    Wessman, Sten
    RISE, Swerea, Swerea KIMAB.
    Scanning Kelvin probe force microscopy study of chromium nitrides in 2507 super duplex stainless steel - Implications and limitations2011Conference paper (Refereed)
    Abstract [en]

    The effect of chromium nitrides on localized corrosion resistance of 2507 super duplex stainless steel was investigated in this study. The Volta potential difference measured with scanning Kelvin probe force microscopy (SKPFM) indicates that chromium nitrides with the size range of 80-230 nm precipitated isothermally at the ferrite/austenite phase boundaries may detrimentally affect the corrosion resistance due to the observed local Volta potential drop at the phase boundaries. Small quenched-in nitrides with the size range of 50-100 nm formed in the centre of the ferrite phase, on the other hand, may have small or no adverse effect on the corrosion resistance since they showed no difference in Volta potential relative to the matrix. © 2010 Elsevier Ltd All rights reserved.

  • 464.
    Wessman, Sten
    et al.
    RISE, Swerea, Swerea KIMAB.
    Hertzman, S.
    Outokumpu Stainless Research Foundation.
    Pettersson, R.
    RISE, Swerea, Swerea KIMAB.
    Lagneborg, R.
    RISE, Swerea, Swerea KIMAB.
    Liljas, M.
    Outokumpu Stainless AB.
    On the effect of nickel substitution in duplex stainless steel2008In: Materials Science and Technology, ISSN 0267-0836, E-ISSN 1743-2847, Vol. 24, no 3, p. 348-355Article in journal (Refereed)
    Abstract [en]

    The present experimental and theoretical study investigates the effect of nickel on the phase balance and resulting properties of a 22Cr duplex stainless steel. The decrease in nickel was balanced by nitrogen and manganese additions. It was found that a minimum nickel content was required to maintain mechanical and corrosion properties at technically relevant levels. The influence of increasing nitrogen content on resulting phase composition and properties is discussed. © 2008 Institute of Materials, Minerals and Mining.

  • 465.
    Wessman, Sten
    et al.
    RISE, Swerea, Swerea KIMAB.
    Karlsson, L.
    ESAB AB.
    Pettersson, R.
    Outokumpu Stainless AB.
    Östberg, A.
    AB Sandvik Materials Technology.
    Computational thermodynamics study of the influence of tungsten in superduplex stainless weld metal2012In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 56, p. 79-87Article, review/survey (Refereed)
    Abstract [en]

    Tungsten is used by some duplex stainless steel producers for partial substitution of molybdenum, both elements enhancing the corrosion resistance of duplex stainless steel. The negative aspect of both molybdenum and tungsten alloying is that they increase the tendency to precipitate intermetallic phases, which may have a detrimental effect on corrosion and mechanical properties. The temperature region for intermetallic phase precipitation is about 700-1000 C, depending on alloy composition, and the time for precipitation is within minutes for superduplex steels.There has been scientific discussion on the relative effects of Mo alone or Mo-W on intermetallic precipitation behaviour in superduplex steels for the past two decades. While the base material response to ageing and precipitation of intermetallic phases has been satisfactorily assessed, weld metal has proved more of a challenge. The main reason for this is that welding is a very complex process introducing many parameters to the assessment which not have to be considered in studies of base material. For example superduplex weld metal typically solidify fully ferritic but may in case excessive nitrogen is added solidify as a mixture of ferrite and austenite. The solidification mode may vary also between weld passes as a consequence of minor variations in composition. Ferritic solidification is the preferred mode, giving the well known Widmanstätten austenite, which forms in the solid state during cooling. Mixed mode solidification gives a vermicular appearance, which is known to increases the tendency to intermetallic formation. A comprehensive study using computational thermodynamics was done to investigate this matter. This study included equilibrium calculations, Scheil-Gulliver solidification simulations, and calculations of the driving force for intermetallic phase precipitation and further a study of diffusion of Mo and W in these alloy systems. The different approaches were applied on model superduplex weld metals with nominal compositions matching commercial superduplex fillers available today. The principal conclusion is that all thermodynamic calculations clearly indicates the W containing filler to show a more pronounced sensitivity to heat treatments by precipitation of intermetallic phases. © 2012 International Institute of Welding.

  • 466.
    Wessman, Sten
    et al.
    RISE, Swerea, Swerea KIMAB.
    Pettersson, R.
    Outokumpu Stainless AB.
    Hertzman, S.
    Outokumpu Stainless Research Foundation.
    On phase equilibria in duplex stainless steels2010In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 81, no 5, p. 337-346Article in journal (Refereed)
    Abstract [en]

    The equilibrium conditions of four duplex stainless steels; Fe-23Cr-4.5Ni-0.1N, Fe-22Cr-5.5Ni-3Mo-0.17N, Fe-25Cr-7Ni-4Mo-0.27N and Fe-25Cr-7Ni-4Mo-1W-1.5Cu-0.27N were studied in the temperature region from 700 to 1000 8C. Phase compositions were determined with SEM EDS and the phase fractions using image analysis on backscattered SEM images. The results showed that below 1000° the steels develop an inverse duplex structure with austenite and sigma phase, of which the former is the matrix phase. With decreasing temperature, the microstructure will be more and more complex and finely dispersed. The ferrite is, for the higher alloyed steels, only stable above 1000 ° and at lower temperatures disappears in favour of intermetallic phases. The major intermetallic phase is sigma phase with small amounts of chi phase, the latter primarily in high Mo and W grades. Nitrides, not a focus in this investigation, were present as rounded particles and acicular precipitates at lower temperatures. The results were compared to theoretical predictions using the TCFE5 and TCFE6 databases.

  • 467.
    Wessman, Sten
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Pettersson, Rachel
    Jernkontoret, Sweden.
    Application of computational thermodynamics to predict growth of intermetallic phases in superduplex stainless steels2015In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 86, no 11, p. 1339-1349Article in journal (Refereed)
    Abstract [en]

    Computational thermodynamics were used to predict the growth of intermetallic phases in superduplex stainless steels, assuming that it is the ferrite which primarily decomposes during heat treatments below 1000°C. Sigma and chi phase were modeled to form at the edge of a 10μm ferrite unit and the time from 0.1s to the development of a 100nm layer of the phase in question was evaluated. This approach encompasses thermodynamics and kinetics of growth of the intermetallic phases but omits nucleation. Nevertheless the calculations accurately predict the classic C-shaped TTT curves, in which "nose" the growth is most rapid with a critical combination of precipitation, diffusion, and driving force. Verification of the relevance of the model was done by comparison with a publication with experimental studies of molybdenum and tungsten alloyed superduplex stainless steel weld metals, showing that partial substitution of Mo of by W does cause a more rapid growth of intermetallic phases. In addition the effect of the partial substitution of nickel by copper was examined and showed that copper decreases the amount of sigma phase and also reduces its growth rate. The results also suggest that the time for nucleation is of less importance in this context than previously suggested and thermodynamics and kinetics are sufficient to give an adequate explanation to the experimental results.

  • 468.
    Wessman, Sten
    et al.
    RISE, Swerea, Swerea KIMAB.
    Selleby, M.
    KTH Royal Institute of Technology.
    Evaluation of austenite reformation in duplex stainless steel weld metal using computational thermodynamics2014In: Welding in the World, ISSN 0043-2288, E-ISSN 1878-6669, Vol. 58, no 2, p. 217-224Article in journal (Refereed)
    Abstract [en]

    This paper provides a theoretical study of austenite reformation during cooling of duplex stainless weld metal using computational thermodynamics and kinetics. Model alloys of the superduplex 2509 weld metal and 2205 base material were used for the study and austenite reformation was calculated at equilibrium conditions and at cooling rates from 0.01 to 2,000 K/s. The calculations also provided the possibility to study the distribution of the alloying elements at ferrite and austenite phase boundaries. The importance of nitrogen for austenite reformation at rapid cooling was studied by comparing with simulations for a low-nitrogen alloy. The results were also compared with experimental and model results from the literature providing good correlation and the unique possibility to study the distribution of alloying elements between the growing austenite and the shrinking ferrite. © 2013 International Institute of Welding.

  • 469.
    Wessman, Sten
    et al.
    RISE, Swerea, Swerea KIMAB.
    Wilson, A.
    AB Sandvik Materials Technology.
    Hertzman, S.
    Outokumpu Stainless Research Foundation.
    Pettersson, R.
    Jernkontoret.
    An experimental and theoretical evaluation of microstructure coarsening in duplex stainless steels2013In: Steel Research International, ISSN 1611-3683, E-ISSN 1869-344X, Vol. 84, no 11, p. 1126-1137Article in journal (Refereed)
    Abstract [en]

    The coarsening of duplex stainless steel microstructures at temperatures above 1000°C was investigated experimentally and theoretically. Hot-rolled duplex 2205 and superduplex 2507 samples were heat treated isothermally at 1100°C up to 700 h, and also between 1000 and 1250°C for 24 h. The ferrite content and the microstructure coarseness, quantified by the measured austenite spacing, AS, were evaluated. It was found that the observed coarsening could be described using Ostwald ripening theory expressed as AS n-AS0 n=kt, where AS0 is austenite spacing of the as-delivered material, k the rate constant, n the exponent, and t the heat treatment time. Using regression analysis, n and k were evaluated and the resulting predictions compared with literature theories and results. The results were also calculated according to the original Lifshitz, Slyozov, Wagner (LSW) theory with parameters taken from literature, as well as with the Dictra software for diffusion and growth in multicomponent systems. The calculations indicated that while the classical LSW theory failed to give a good description of the experimental results, the Dictra simulations proved very accurate, even though systems of equal ferrite and austenite content are considerably outside the intended range of applicability of the software. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  • 470.
    Weyler, Simone
    et al.
    RISE, Swerea, Swerea KIMAB.
    Bengtson, Arne
    RISE, Swerea, Swerea KIMAB.
    The hydrogen effect as a function of discharge parameters: Investigations of the variation of emission yield in glow discharge plasmas2010In: Journal of Analytical Atomic Spectrometry, ISSN 0267-9477, E-ISSN 1364-5544, Vol. 25, no 6, p. 849-855Article in journal (Refereed)
    Abstract [en]

    It is well known that traces of hydrogen in the glow discharge plasma enhance or suppress the intensities of other spectral lines, in this work termed "the hydrogen effect". In this work, the focus is on the variation of the hydrogen effect as a function of the discharge parameters, for the purpose of developing effective correction methods in quantitative depth profile analysis. A simple, but effective experimental method was employed: The intrinsic contamination of the source leads to an increased amount of hydrogen in the plasma at the beginning of the discharge, which is rapidly reduced with sputtering time. Thus, by recording the intensity depth profiles of multi-element bulk reference materials, the influence of hydrogen on several emission lines can be observed. The decay or increase in intensity, correlated to the intensity of the hydrogen emission line, gives the desired information. Systematic investigations by varying current and voltage in a considerable range provided a good matrix of data to find a model describing these variations. Furthermore, renewed investigations of the variation of emission yields (EY) with discharge parameters have led to a model which has been used to correct the obtained data for the hydrogen intensities, so as to represent the actual content of hydrogen in the plasma. The information extracted from these studies is expected to be of great importance for routine depth profile analysis, as the hydrogen correction is a relevant tool in software quantification algorithms. Existing correction models for the hydrogen effect do not take variations in the discharge parameters into account. This work clearly shows that it is necessary to implement such variations for accurate correction. © The Royal Society of Chemistry 2010.

  • 471.
    Winther, Thea
    et al.
    Swedish National Heritage Board, Sweden.
    Bannerman, Judith
    Swedish National Heritage Board, Sweden.
    Skogstad, Hilde
    Swedish National Heritage Board, Sweden.
    Johansson, Mats K. G.
    KTH Royal Institute of Technology, Sweden.
    Jacobson, Karin
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Samuelsson, Johan
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Adhesives for adhering polystyrene plastic and their long-term effect2015In: Studies in Conservation, ISSN 0039-3630, E-ISSN 2047-0584, Vol. 60, no 2, p. 107-120Article in journal (Refereed)
    Abstract [en]

    To guide conservators in their decisions in active conservation of polystyrene materials, seven adhesives were tested before and after light ageing. The material was investigated by assessment of working properties, appearance, colour measurement, tensile testing, hardness measurement, assessment of break type, scanning electron microscope imaging, and assessment of reversibility. Based on a survey among conservators, the adhesives included were acrylates (Paraloid® B-72 in acetone: ethanol, or only ethanol, Paraloid® B-67 in isopropanol, Primal® AC 35, Acrifix® 116), epoxies (HXTAL®-NYL-1, Araldite ® 2020) and one cyanoacrylate (Loctite® Super Attack Precision). Adhesives were tested on extruded sheets of transparent, general purpose polystyrene applied on joined edges and as an open layer. Damage to the plastic could be seen for Acrifix® 116 and Loctite® Super Attack Precision. The average break force sensitivity values indicate that the cyanoacrylate was weakened while Acrifix® 116 was strengthened after ageing. In general, the cyanoacrylate was the strongest and Paraloid® B-67 the weakest. Most adhesives showed yellowing after ageing apart from Acrifix® 116 and HXTAL®-NYL-1. The Paraloids, Primal® AC 35, and the epoxies were possible to remove from the plastic.

  • 472.
    Wirdelius, Håkan
    et al.
    Chalmers University of Technology, Sweden.
    Malmström, Mikael
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB.
    Diujster, Arno
    TNO, The Netherlands.
    Volker, A
    TNO, The Netherlands.
    Krix, D
    Salzgitter Mannesmann Forschung GmbH, Germany.
    Stolzenberg, M
    Salzgitter Mannesmann Forschung GmbH, Germany.
    Martinez-de-Guerenu, A
    CEIT, Spain.
    Gutierrez, I
    CEIT, Spain.
    Jorge-Badiola, D
    CEIT, Spain.
    van den Berg, FD
    Tata Steel, The Netherlands.
    Kok, PJJ
    Tata Steel, The Netherlands.
    Validation of models for Laser Ultrasonic spectraas a function of the grain size in steel2018Conference paper (Refereed)
    Abstract [en]

    To reduce costs of production and increase economic sustainability it is necessary to introducequality assessment in an early stage in the manufacturing process. In the European project(Product Uniformity Control – PUC), the intention is to use ultrasonic information to assessmicrostructure parameters that are related to macroscale qualities such as mechanicalproperties. Laser induced ultrasonic technique (LUS) requires no media and can generate anddetect ultrasonic information at some distance from the component. This technique is thereforeaddressed within this project as a solution to measure ultrasonic properties in an industrialenvironment.Mathematical modelling of the ultrasonic wave propagation problem has been used in order toget a deeper understanding of the physics and to identify ultrasonic properties that can be usedas an indirect measurement of grain size. The use of both analytical and numerical modelsenabled extensive parametric studies together with investigation of ultrasonic interactions withwell-defined individual microstructures.The LUS technique has previously been applied to e.g. monitor grain growth duringthermomechanical processing of metals. These applications identified and used a correlationwith the frequency content of the attenuation. This have been investigated as a possible indirectmeasurement of grain size, also in this project. The models have been used to verify thecorrelations and to evaluate different procedures that could be applied as an industrial solution.The suggested procedure is based on deconvolving two successive echoes and has beenexperimentally validated by two different LUS systems. The reference samples used in thevalidation were produced by changing the annealing temperature and time to obtain a variationin grain sizes. These grain sizes were then identified by EBSD and the samples were examinedin terms of grain size influence on spectral attenuation.

  • 473.
    Wredenberg, Fredrik
    et al.
    RISE, Swerea, Swerea KIMAB.
    Björkblad, Anders
    RISE, Swerea, Swerea KIMAB.
    SK Brott – optimering av brottmekanisk provstav för sega material2013Report (Refereed)
    Abstract [sv]

    Föreliggande arbete är genomfört som ett samarbetsprojekt mellan Swerea KIMAB AB och kärnkraftverkens materialgrupp. Vid brottmekanisk provning av sega material (typiskt nickelbaslegeringar) får man problem vilka delvis beror på att förlängningsvärdena är så stora att det inte längre går att använda normal lineär brottmekanik. En av de bakomliggande orsakerna till att man stöter på svårigheter är att randeffekterna vid provens ytterkanter blir betydande. Detta i sin tur gör att man måste upp till orealistiska bredder på provstavarna för att rimligt hålla sig inom reglementet för lineär brottmekanik. Grundidén i detta arbete var att nyttja FEM och numerisk optimering för att formge en brottmekanisk provstav på ett sådant sätt att belastningen blir jämn längs sprickfronten och att randeffekterna blir så små att dom kan accepteras. Det kan med andra ord uttryckas som smart design. Den geometri som användes var CT-provstaven. För att åstadkomma önskade utfall applicerades dels sidospår på vas sida längs sprickfronten, dels två hål igenom provstaven. Sidospårens uppgift var att minska randeffekten mot stavens yta och den formades via optimering så att den fick en lämplig utformning under belastning. De två hålen hade till uppgift att ”försvaga” materialet (styvheten) i den centrala delen av sprickfronten. Denna extra frihetsgrad visar sig vara behövlig för att komma fram till en lämplig formgivning. För att bedöma resultaten gjordes jämförelser mot en provstavsbredd om 75 mm, det som inom kärnkraftssektorn bedöms ge acceptabla värden. Resultaten visar att det går att ta ned tjockleken ca 20 % jämfört mot den ”acceptabla provstavsdimension” som idag används med användande av lämpligt utformade sidospår samt genomgående avlastningshål.

  • 474.
    Wredenberg, Fredrik
    et al.
    RISE, Swerea, Swerea KIMAB.
    Larsson, P.-L.
    Royal Institute of Technology.
    On the stability of delamination growth at scratching of thin film structures2011In: JCT Research, ISSN 1547-0091, E-ISSN 2168-8028, Vol. 8, no 6, p. 707-717Article in journal (Refereed)
    Abstract [en]

    Scratching of thin film/substrate structures is studied theoretically and numerically. The results are discussed in connection to delamination initiation and in particular subsequent growth at scratching. The material behavior of the film is described by classical elastoplasticity accounting for large deformations. The deformation of the substrate is neglected indicating that the results are pertinent to soft thin films. The numerical investigation is performed using the finite element method (FEM) and the numerical strategy is discussed in some detail. The results from this study show that delamination growth at thin film scratching is a stable feature with crack arrest occurring at a decreasing load. © 2011 ACA and OCCA.

  • 475.
    Wu, Rui
    RISE, Swerea, Swerea KIMAB.
    Processing line inclusion (PLI) and joint line hooking (JLH) in Cu-OFP friction stir weld – part 1: metallographic examinations2011Report (Refereed)
    Abstract [en]

    Six samples were extracted at positions 16°, 42°, 67°, 98.5°, 123°, and 338° from a circle friction stir weld (FSW) of Cu-OFP, designated internally FSWL08/KL059, in order to examine if there is processing line inclusions (PLI) in the FSW. The samples were metallographically prepared, were annealed in hydrogen, and were electrolytically polished and etched, respectively. The samples were examined macro- and microscopically. Chemical compositions of the particles/inclusions inside PLI were quantitatively determined. The PLI did find on the retreating side of FSW on all six investigated samples. Usually, the PLI consists of two parts, an axial PLI and a radial PLI. The axial PLI, commonly 1~2 mm long, occurred about 7~9 mm right above the joint line hooking (JLH) in the FSW. It is often separated and crack-like. It is thought to be a remaining part of slit/JLH. The radial PLI continued from the axial PLI and followed to a large extent the contour of processing line on the retreating side. It could be as long as the processing line. The axial PLI at the position 42° went through entire thickness of the investigated sample, indicating that it is very likely that the axial PLI may have penetrated all the way along the FSW. Particles/inclusions were detected inside the PLI. The particles/inclusions consist of mainly silicon-oxide, as well as aluminium-, potassium-, calcium-, and sodium-oxides. In the present case, both hydrogen annealing and electrolytic polishing and etching revealed the PLI effectively and apparently. The JLH bent downwards and towards the outer surface. It was about 3.5~5 mm away from the root of the FSW. It is recommended to carry out tensile and creep tests to determine and to evaluate the PLI’s impact on the integrity of copper canisters. Keywords: Processing line inclusions (PLI), joint line hooking (JLH), Cu-OFP, friction stir (FSW), metallography, hydrogen annealing, electrolytic polishing and etching, oxide, integrity.

  • 476.
    Wu, Rui
    et al.
    RISE, Swerea, Swerea KIMAB.
    Pettersson, Niklas
    RISE, Swerea, Swerea KIMAB.
    Martinsson, Åsa
    RISE, Swerea, Swerea KIMAB.
    Sandström, Rolf
    RISE, Swerea, Swerea KIMAB.
    Cell structure in cold worked and creep deformed phosphorus alloyed copper2014In: Materials Characterization, ISSN 1044-5803, E-ISSN 1873-4189, Vol. 90, p. 21-30Article in journal (Refereed)
    Abstract [en]

    Transmission electron microscopy (TEM) examinations on as-received, cold worked, as well as cold worked and creep tested phosphorus-alloyed oxygen-free copper (Cu-OFP) have been carried out to study the role of the cell structure. The cell size decreased linearly with increasing plastic deformation in tension. The flow stress in the tests could also be correlated to the cell size. The observed relation between the flow stress and the cell size was in excellent agreement with previously published results. The dense dislocation walls that appeared after cold work in tension is likely to be the main reason for the dramatic increase in creep strength. The dense dislocation walls act as barriers against dislocation motion and their presence also reduces the recovery rate due to an unbalanced dislocation content. © 2014 Elsevier Inc.

  • 477.
    Wu, Rui
    et al.
    RISE, Swerea, Swerea KIMAB.
    Sandström, Rolf
    RISE, Swerea, Swerea KIMAB.
    Influence of multiaxial stresses on creep properties of phosphorus alloyed oxygen free copper2010Conference paper (Refereed)
    Abstract [en]

    Phosphorus alloyed oxygen free copper (Cu-OFP) canisters are planned to be used for spent nuclear fuel in Sweden. The copper canisters will be subjected to creep under multiaxial stress states in the repository. Creep tests have therefore been carried out using double notch specimens having a notch acuity of 0.5 in Cu-OFP at 75°C. The creep results from the notched specimens are compared with those from the smooth ones. It shows that the creep lifetime for notched specimens can be estimated to be two orders of magnitude or more longer than that for the smooth ones, indicating notch strengthening for the investigated Cu-OFP material. Metallographic examinations after failure show that pores and creep cavities to a limited extent are observed only adjacent to fracture. To interpret the tests for the notched creep specimens, finite element computations have been performed with a new basic model for primary creep without fitting parameters. The creep strain versus time could be simulated successfully. Initially the stresses at the notches are almost twice as high as in the centre of the specimens. The highest stresses are relaxed rapidly. At the studied temperature 75°C, the creep exponent of Cu-OFP is about 85, thus, deep down in the power-law breakdown regime. This contributes strongly to the homogenous stress distribution across the centre section. Since the redistribution of stresses has taken place before large creep deformation has occurred, the specimens are not notch sensitive in agreement with observations. Copyright © 2009 by ASME.

  • 478.
    Wu, Rui
    et al.
    RISE, Swerea, Swerea KIMAB.
    Sandström, Rolf
    RISE, Swerea, Swerea KIMAB.
    Jin, L.-Z.
    Royal Institute of Technology.
    Creep crack growth in phosphorus alloyed oxygen free copper2013In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 583, p. 151-160Article in journal (Refereed)
    Abstract [en]

    Creep crack growth (CCG) has been studied in phosphorus-alloyed oxygen-free copper (Cu-OFP) at 22, 75, 175, and 215. °C with compact tension (CT) specimens. At 175 and 215. °C, the cracks grew about 10. mm before final instantaneous failure. In contrast, there was no visible crack growth at 22 and 75. °C. Strongly deformed grains were observed adjacent to the cracks at 175 and 215. °C. Intergranular creep cavities were found around the cracks. At 22 and 75. °C, deformed grains and some cavities as well as microcracks were observed close to the crack tip.A model for crack propagation based on creep damage formation has been formulated to interpret the test results. Rupture criteria based on both creep ductility exhaustion and grain boundary cavitation were taken into account. The contribution from the ductility exhaustion to the creep damage dominated at the lower two test temperatures whereas the contribution from grain boundary cavitation at the higher test temperatures. The model can describe the influence of temperature on the observed creep crack propagation. It can also account for the observed cavitation in a qualitative way. © 2013 Elsevier B.V.

  • 479.
    Yasri, Maria
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB. Université de Bretagne Occidentale, France; Telecom Bretagne,France.
    Lescop, B.
    Université de Bretagne Occidentale, France.
    Diler, Erwan
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Gallée, F.
    Telecom Bretagne, France.
    Thierry, Dominique
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Rioual, S.
    Université de Bretagne Occidentale, France.
    Monitoring uniform and localised corrosion by a radiofrequency sensing method2018In: Sensors and actuators. B, Chemical, ISSN 0925-4005, E-ISSN 1873-3077, Vol. 257, p. 988-992Article in journal (Refereed)
    Abstract [en]

    A new method for atmospheric corrosion monitoring based on the variation of radiofrequency (RF) wave propagation in a resonator during its corrosion is presented. The ability of the proposed sensor to differentiate between uniform and localized corrosion mechanisms is demonstrated by considering two identical open stub microstrip resonators produced in zinc and aluminum materials, respectively. For that purpose, experimental characterization of electromagnetic wave propagation in the resonators and simulations are compared. The proposed sensitive resonator should therefore be considered as the key element of new corrosion mimetic sensors.

  • 480.
    Yasri, Maria
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB. Technopôle Brest-Iroise, France; Université de Bretagne Occidentale, France.
    Lescop, Benoit
    Université de Bretagne Occidentale, France.
    Gallee, Francois
    Technopôle Brest-Iroise, France.
    Diler, Erwan
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Thierry, Dominique
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Rioual, Stephane
    Universite de Bretagne Occidentale, France.
    Microwave characterization of materials during corrosion: Application to wireless sensors2015In: European Microwave Week 2015: "Freedom Through Microwaves", EuMW 2015 - Conference Proceedings; 2015 45th European Microwave Conference Proceedings, EuMC, Institute of Electrical and Electronics Engineers Inc. , 2015, p. 267-270Conference paper (Refereed)
    Abstract [en]

    A new method for corrosion monitoring of metals and alloys is presented. It is based on the change of the radiofrequency (RF) wave propagation in a microstrip line during its corrosion. The microstrip line is produced in the same metal as the mechanical structure under monitoring. The studied frequencies correspond to the ISM bands. During the corrosion process, measured transmission decreases from 0 to 40 dB. This lost is clearly explained by simulations. Consequently, experimental data and simulations results provide fundamental basis on the sensing mechanisms of the method and evidence, in particular, the possibility to distinguish between localized and uniform corrosion. Due to the nature of the method, the sensitive microstrip can be very easily integrated through different architectures into RF wireless sensors. As the consequence, the proposed method should be considered as promising and reliable tool for corrosion monitoring of several materials exposed to various environments.

  • 481.
    Yuan, Kang
    et al.
    Linköping University, Sweden.
    Lin Peng, Ru
    Linköping University, Sweden.
    Li, Xin-Hai
    Siemens Industrial Turbomachinery AB, Sweden.
    Talus, Annika
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Johansson, Sten
    Linköping University, Sweden.
    Wang, Yan-Dong
    University of Science and Technology, China.
    Hot corrosion of MCrAlY coatings in sulphate and SO2 environment at 900°C: Is SO2 necessarily bad?2015In: Surface & Coatings Technology, ISSN 0257-8972, E-ISSN 1879-3347, Vol. 261, p. 41-53Article in journal (Refereed)
    Abstract [en]

    MCrAlY coatings can be corroded due to the basic fluxing (type-I hot corrosion) of the supposed-to-be protective alumina scale in a molten sulphate environment. In this study, two MCrAlY coatings, coating A (10wt.% Al, 20wt.% Cr) and coating B (7wt.% Al, 28wt.% Cr), were tested in 48-hour cycles at 900°C in a sodium-potassium sulphate environment with and without SO2 (500ppm). The aim was to study the effect of SO2 at the typical type-I-hot-corrosion temperature-900°C. The results showed that the corrosion behavior of the MCrAlY coatings depended not only on the coating composition but also on the corrosion environment. It was found that in coating A alumina scale was more resistant in the sulphate-plus-SO2 condition than that in the sulphate-only condition. Such phenomenon indicated a beneficial effect of SO2. On Coating B, however, mixed oxide layers, consisting of alumina and other oxides and sulfides, formed after a certain number of cycles in the sulphate environments with or without SO2 gas. In this coating, the addition of SO2 in the sulphate environment promoted the formation of non-dense chromia oxides which may form from oxidation of Cr-sulfides.

  • 482.
    Zajac, Stanislaw
    et al.
    RISE, Swerea, Swerea KIMAB.
    Hutchinson, Bevis
    RISE, Swerea, Swerea KIMAB.
    Lagneborg, Rune
    RISE, Swerea, Swerea KIMAB.
    Ferrite grain refinement in seamless pipes through intragranular nucleation on VN2008In: 3rd International Conference on Thermomechanical Processing of Steels, TMP 2008, 2008Conference paper (Refereed)
    Abstract [en]

    Mill rolling process of seamless pipe was simulated with the aim of applying grain refinement through the formation of intragranular ferrite on VN precipitated inside austenitic grains, for production of as-hot rolled microstructures, which are currently attained only by in-line normalising. Tests were performed on V+N and V+N(Ti) steels using two types of schedules with long and short transfer/heating times prior to sizing between 930-830°C. It was found that transfer/heating time between high temperature rolling and low temperature sizing could be used for precipitation of VN in austenite which in turn can nucleate intragranular ferrite grains on cooling. To facilitate the precipitation process of VN a sub-micro-addition of Ti was used which also helps to restrain austenite grain growth during piercing and pipe forming. Subsequent V(C,N) precipitation of the remaining vanadium in the ferrite contributes precipitation strengthening. Hot rolling followed by intragranular ferrite formation in 0.1%V-0.015%N-0.005%Ti steel is able to develop a fine ferritepearlite microstructure with an average ferrite grain size of 7um.

  • 483.
    Zajac, Stanislaw
    et al.
    RISE, Swerea, Swerea KIMAB.
    Hutchinson, Bevis
    RISE, Swerea, Swerea KIMAB.
    Lagneborg, Rune
    RISE, Swerea, Swerea KIMAB.
    Korchynsky, M.
    STRATCOR.
    Ferrite grain refinement in seamless pipes through intergranular nucleation on VN2009In: La Metallurgia Italiana, ISSN 0026-0843, Vol. 101, no 2Article in journal (Refereed)
    Abstract [en]

    Mill rolling process of seamless pipe was simulated with the aim of applying grain refinement through the formation of intragranular ferrite on VN precipitated inside austenitic grains, for production of as-hot rolled microstructures, which are currently attained only by in-line normalising. Tests were performed on V+N and V+N(Ti) steels using two types of schedules with long and short transfer/heating times prior to sizing between 930-830°C. It was found that transfer/heating time between high temperature rolling and low temperature sizing could be used for precipitation of VN in austenite which in turn can nucleate intragranular ferrite grains on cooling. To facilitate the precipitation process of VN a sub-micro-addition of Ti was used which also helps to restrain austenite grain growth during piercing and pipe forming. Subsequent V(C,N) precipitation of the remaining vanadium in the ferrite contributes precipitation strengthening. Hot rolling followed by intragranular ferrite formation in 0.1%V-0.015%N-0.005%Ti steel is able to develop a fine ferrite-pearlite microstructure with an average ferrite grain size of 7um.

  • 484.
    Zetterberg, Mikaela
    RISE, Swerea, Swerea KIMAB.
    A critical overview of machining simulations in ABAQUS2014Report (Refereed)
    Abstract [en]

    Metal cutting is one of the most commonly occurring manufacturing processes in the industry and major effort is made to improve its processes. Cutting tools are expensive and have a life length measured in minutes, why predictions of tool wear are of great interest. Finite Element (FE) simulations have a central role in the development of tools and cutting processes, but performing simulations of metal cutting is not easy. The method chosen for the chip formation has a large impact on the result of the simulations. The scope of this work includes a survey on important parameters and different possibilities to form a chip in simulations of metal cutting in ABAQUS/Explicit. Particular emphases are placed the on prediction of flank wear and how the hardening implemented in the material model effects this. The approach has been to start with a literature study and thereafter make simulations in ABAQUS/Explicit. FE simulations, of cutting, with different damage criteria and simulations with SPH (Smooth Particle Hydrodynamics)- method are presented. None of the possibilities to form a chip in ABAQUS/Explicit, as implemented today, seems to be sufficient for simulations of cutting to predict flank wear. The SPH-method will be a good alternative for simulations of metal cutting in ABAQUS/Explicit if temperature dependency is implemented. The material model in general, the type of hardening in specific, has an impact on the chip-form and the stress state in the chip and workpiece. And thereby effects the flank wear.

  • 485.
    Zhang, F.
    et al.
    KTH Royal Institute of Technology.
    Sababi, M.
    KTH Royal Institute of Technology.
    Brinck, T.
    KTH Royal Institute of Technology.
    Persson, Dan
    RISE, Swerea, Swerea KIMAB.
    Pan, J.
    KTH Royal Institute of Technology.
    Claesson, P.M.
    KTH Royal Institute of Technology.
    In situ investigations of Fe3+ induced complexation of adsorbed Mefp-1 protein film on iron substrate2013In: Journal of Colloid and Interface Science, ISSN 0021-9797, E-ISSN 1095-7103, Vol. 404, p. 62-71Article in journal (Refereed)
    Abstract [en]

    A range of in situ analytical techniques and theoretical calculations were applied to gain insights into the formation and properties of the Mefp-1 film on iron substrate, as well as the protein complexation with Fe3+ ions. Adsorption kinetics of Mefp-1 and the complexation were investigated using QCM-D. The results suggest an initially fast adsorption, with the molecules oriented preferentially parallel to the surface, followed by a structural change within the film leading to molecules extending toward solution. Exposure to a diluted FeCl3 solution results in enhanced complexation within the adsorbed protein film, leading to water removal and film compaction. In situ Peak Force Tapping AFM was employed for determining morphology and nano-mechanical properties of the surface layer. The results, in agreement with the QCM-D observations, demonstrate that addition of Fe3+ induces a transition from an extended and soft protein layer to a denser and stiffer one. Further, in situ ATR-FTIR and Confocal Raman Micro-spectroscopy (CRM) techniques were utilized to monitor compositional/structural changes in the surface layer due to addition of Fe3+ ions. The spectroscopic analyses assisted by DFT calculations provide evidence for formation of tri-Fe3+/catechol complexes in the surface film, which is enhanced by Fe3+ addition. © 2013 The Authors.

  • 486.
    Zhang, Yafan
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Hammam, Tag
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB.
    Belov, Ilja
    Jönköping University, Sweden.
    Sjögren, Torsten
    RISE - Research Institutes of Sweden, Safety and Transport, Safety.
    Bakowski, Mietek
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Nee, Hans Peter
    KTH Royal Institute of Technology, Sweden.
    Thermomechanical Analysis and Characterization of a Press-Pack Structure for SiC Power Module Packaging Applications2017In: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 7, no 7, p. 1089-1100Article in journal (Refereed)
    Abstract [en]

    This paper presents an experimental methodology for the characterization of thermomechanical displacement and friction properties in a free-floating press-pack structure, and evaluation of the tensile stress on the semiconductor die through simulation of different mechanical and thermal loading conditions. The press-pack structure consists of a single silver-metallized (1 μm) silicon carbide die (400 μm) in contact with rhodium-coated (0.4 μm) molybdenum square plates. The thermomechanical displacements in the press-pack structure have been obtained using the digital image correlation technique, and the mean random error has been $± $0.1 μm, which is approximately 10 ppm of the measured length (10.5 mm). The developed experimental method has led to an analytical estimation of friction coefficients on the interfaces' silicon carbide-molybdenum and molybdenum-copper. The results demonstrate that the thin silver layer behaves as a solid film lubricant. A 2-D finite-element model representing the experimental setup has been implemented. The difference in displacement between measurement and simulation is less than 8%. Furthermore, the coinfluence of the design parameters on the thermomechanical performance of the stacked structure has been analyzed through simulations. Finally, design guidelines to reduce the tensile stress on the silicon carbide die have been proposed regarding free-floating press-pack power electronics packaging.

  • 487.
    Zhang, Yafan
    et al.
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Nee, Hans Peter
    KTH Royal Institute of Technology, Sweden.
    Hammam, Tag
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Belov, Ilja
    Jönköping University, Sweden.
    Ranstad, Per
    GE Power Sweden AB, Sweden.
    Bakowski, Mietek
    RISE - Research Institutes of Sweden, ICT, Acreo.
    Multiphysics Characterization of a Novel SiC Power Module2019In: IEEE Transactions on Components, Packaging, and Manufacturing Technology, ISSN 2156-3950, E-ISSN 2156-3985, Vol. 9, no 3, p. 489-501Article in journal (Refereed)
    Abstract [en]

    This paper proposes a novel power module concept specially designed for highly reliable silicon carbide power devices for medium- and high-power applications. The concept consists of two clamped structures: 1) a press-pack power stage accommodating silicon carbide power switch dies, and 2) perpendicularly clamped press-pack heatsinks, in which, the heatsinks are in contact with electrically insulated case plates of the power stage. The concept enables bondless package with symmetric double-sided cooling of the dies and allows for an order of magnitude higher clamping force on the heatsinks than what can be applied on the dies. The concept has been evaluated in a first demonstrator (half-bridge configuration with ten paralleled silicon carbide dies in each position). Experimental methodologies, setups, and procedures have been presented. The commutation loop inductance is approximately 9 nH at 78 kHz. The junction-to-case thermal resistance is approximately 0.028 K/W. Furthermore, a simplified 3D finite element thermomechanical model representing the center unit of the demonstrator, has been established for the purpose of future optimization. The accuracy of the simulated temperatures is within 4 % compared to the measurements. Finally, a 3D thermomechanical stress distribution map has been obtained for the simplified model of the demonstrator.

  • 488.
    Ånmark, Niclas
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB. KTH Royal Institute of Technology, Sweden.
    Björk, Thomas
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Ganea, Anna
    Sandvik Coromant, Sweden.
    Ölund, Patrik
    Ovako, Sweden.
    Hogmark, Sture
    Uppsala University, Sweden.
    Karasev, Andrey
    KTH Royal Institute of Technology, Sweden.
    Jönsson, Pär Göran
    KTH Royal Institute of Technology, Sweden.
    The effect of inclusion composition on tool wear in hard part turning using PCBN cutting tools2015In: Wear, ISSN 0043-1648, E-ISSN 1873-2577, Vol. 334-335, p. 13-22Article in journal (Refereed)
    Abstract [en]

    This work reports on hard part turning of carburizing steels using a PCBN cutting tool in fine machining. Emphasis is on the link between composition of the inclusions in work material and wear mechanisms of the cutting tool. A Ca-treated machinability improved 20NiCrMo steel was included together with three other carburizing steels with different inclusion characteristics. Machining tests were conducted to examine cutting tool life and its balance between excessive flank wear and crater wear. The wear mechanisms were examined using a scanning electron microscope (SEM) equipped with an energy dispersive X-ray spectrometer (EDS) and a secondary electron (SE) detector.The longest tool life was obtained when cutting the Ca-treated steel. The improved machinability is linked to the deposition of complex (Mn,Ca)S and (Ca,Al)(O,S) protective slag layers that form on the rake face of the cutting tool during machining. Cutting in this steel also resulted in a typical ridge formation in the tool edge crater. Transfer of workpiece material to the rake face crater is characteristic in hard part turning of steel with high cleanliness. This is suggested to be related to the lack of the sulfides that lubricate conventional machinability treated steels, and that the crater wear of low-sulfur steel is more pronounced than for steels with higher sulfur content.

  • 489.
    Ånmark, Niclas
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB. KTH Royal Institute of Technology, Sweden.
    Karasev, Andrey
    KTH Royal Institute of Technology, Sweden.
    Jönsson, Pär Göran
    KTH Royal Institute of Technology, Sweden.
    The effect of different non-metallic inclusions on the machinability of steels2015In: Materials, ISSN 1996-1944, E-ISSN 1996-1944, Vol. 8, no 2, p. 751-783Article, review/survey (Refereed)
    Abstract [en]

    Considerable research has been conducted over recent decades on the role of non-metallic inclusions and their link to the machinability of different steels. The present work reviews the mechanisms of steel fractures during different mechanical machining operations and the behavior of various non-metallic inclusions in a cutting zone. More specifically, the effects of composition, size, number and morphology of inclusions on machinability factors (such as cutting tool wear, power consumption, etc.) are discussed and summarized. Finally, some methods for modification of non-metallic inclusions in the liquid steel are considered to obtain a desired balance between mechanical properties and machinability of various steel grades.

  • 490.
    Åslund, Peter
    et al.
    RISE, Swerea, Swerea KIMAB.
    Vomhoff, H.
    STFI-Packforsk AB.
    Waljanson, A.
    STFI-Packforsk AB.
    The deformation of chemical and mechanical pulp webs during suction box dewatering2008In: Nordic Pulp & Paper Research Journal, ISSN 0283-2631, E-ISSN 2000-0669, Vol. 23, no 4, p. 403-408Article in journal (Refereed)
    Abstract [en]

    The deformation of the paper web during and after a suction pulse on initially saturated fibre web made of chemical and mechanical pulp was investigated. A laboratory suction box was used, where the suction time and pressure drop could be varied and controlled. During the experiments, the web thickness, the air flow through the web and the suction pressure were recorded and after the experiments, the dry content of the web was determined. A large deformation was observed when the suction pulse was applied. After the suction pulse, a considerable expansion of the web took place, probably an effect of rewetting. The compression of the web appeared to be the most important dewatering mechanism increasing the dry content of the web. However, if the web is not separated from the forming fabric, rewetting after the suction pulse will greatly reduce the dry content.

  • 491.
    Åström, Björn
    RISE, Swerea, Swerea KIMAB.
    Non destructive evaluation of adhesive bonds2014Report (Refereed)
    Abstract [en]

    Adhesive joining is a method that gains ground within primarily the automotive segment due to the introduction of light weight materials and difficult material combinations. Light weight metals like aluminium, titanium and magnesium along side of polymer matrix composites has been used within the aerospace industry for quite some time, but the production series within the automotive segment is usually significantly longer and the production time usually more limited To be able to work with quality assurance on a continuous basis demands non destructive evaluation methods that are fast, reliable and preferably possible to at least partly automate. There are several non destructive evaluations methods that might meet these demands, e.g. (computerised) visual inspection, shearography, IR thermo-graphy, acoustic emission, computer aided tap testing and a few ultrasonic techniques: Guided Wave inspection and laser ultrasonics. In many cases it is desirable to evaluate a bondline prior to adhesive setting, but due to the basic principles of the evaluations method, the adherends or a combination thereof, this is not always possible. In some cases, however it is possible with considerable potential cost saves as a result. The NDE methods probably best suited for pre setting evaluation is IR thermography and Guided Wave inspection. In some cases visual inspection, possibly computer aided, can be a feasible alternative as well.

  • 492.
    Öhman, Maria
    RISE, Swerea, Swerea KIMAB.
    The evaluation of pre-loaded structural components - A literature survey with focus on rock bolt axial load evaluation employing the ultrasonic bi-wave technique in a non-contact mode2014Report (Refereed)
    Abstract [sv]

    As rock bolts are grouted into e.g. cement or epoxy, only one end is accessible for the analytical technique in question, ultrasonic methods are being considered valuable nondestructive techniques for estimating the bolt integrity. The conventional acoustoelastic ultrasonic technique for deducing the axial loading of prestressed bolts is based on variations in the time-of-flight of a single longitudinal bulk wave with loading. A main drawback of this mono-wave technique is the required pre-knowledge of the initial bolt length and the initial loading condition. The bi-wave method on the other hand allows the axial load in the stressed state to be calculated from the time-of-flight ratio of two different wave types, without preknowledge of measurement in the unstressed state. Commercial piezoelectric probes exist that simultaneously generate and detect both longitudinal and transverse bulk waves, and the bi-wave technique has successfully been used for deducing the axial load of 50-215 mm long bolts. Piezoelectric transducers, however, require an intimate contact with the bolt end why errors rise from various surface conditions and couplant properties. The primary advantage of EMAT transducers over piezoelectric transducers is the ultrasonic wave generation and detection through electromagnetic forces, without requirements for intimate contact with the bolt end. The main drawback of the EMAT systems is; however, the generally low signal-to-noise ratio compared to piezoelectric transducers. Currently no commercial EMAT probe exists for bi-wave applications; however, an EMAT bi-wave prototype equipment has proven capable to measure the axial load condition of bolts with lengths up to 500 mm.

  • 493.
    Öhman, Maria
    et al.
    RISE, Swerea, Swerea KIMAB.
    Persson, Dan
    RISE, Swerea, Swerea KIMAB.
    ATR-FTIR Kretschmann spectroscopy for interfacial studies of a hidden aluminum surface coated with a silane film and epoxy I.: Characterization by IRRAS and ATR-FTIR2012In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 44, no 2, p. 133-143Article in journal (Refereed)
    Abstract [en]

    Interfacial analysis is essential in many areas of interest, for instance within the ongoing research on environmentally friendly pretreatments of metal surfaces. While studies of the hidden interface between a metal and polymer top-coat are of great importance, properties of a surface confined between two media are difficult to analyze in detail. Within the two parts of this study, ATR-FTIR spectroscopy in the Kretschmann geometry is employed as the main analytical tool to study the interface between a thermo-cured epoxy and aluminum pretreated with a silane film. The technique requires model systems based on thin metal films, but in contrast to most analytical techniques it permits the analysis of a hidden interface. Initial characterization of the silane film formed from a pH-regulated γ-APS and BTSE solution was conducted by both ATR-FTIR Kretschmann and IRRAS spectroscopy. Absorption bands were obtained at 1250-900 cm -1, assigned to Si-O functionalities, and at ∼1570 and ∼1410 cm -1 assigned to acetate existing as a counter-ion to γ-APS. After application of the epoxy film, interfacial alterations were detected upon thermal curing including the densification of the epoxy film, the dehydration of aluminum and the formation of molecular epoxy reaction products. Few alterations could be assigned to the silane film. Calculated spectra derived from optical data can verify experimental results and aid data interpretation, and effects of metal oxidation of aluminum were confirmed by introducing gold as an additional substrate. The results showed that ATR-FTIR Kretschmann spectroscopy is clearly a valuable tool for the study of hidden interfaces of stratified media. Copyright © 2011 John Wiley & Sons, Ltd.

  • 494.
    Öhman, Maria
    et al.
    RISE, Swerea, Swerea KIMAB.
    Persson, Dan
    RISE, Swerea, Swerea KIMAB.
    ATR-FTIR Kretschmann spectroscopy for interfacial studies of a hidden aluminum surface coated with a silane film and epoxy II.: Analysis by integrated ATR-FTIR and EIS during exposure to electrolyte with complementary studies by in situ ATR-FTIR and in situ IRRAS2012In: Surface and Interface Analysis, ISSN 0142-2421, E-ISSN 1096-9918, Vol. 44, no 1, p. 105-113Article in journal (Refereed)
    Abstract [en]

    The destabilization of the interface between a polymer and a metal surface is of considerable interest in several application areas, including the ongoing research on environmentally friendly pretreatments as a replacement for the Cr(VI)-containing systems where the understanding of mechanisms and performance of a confined metal/polymer interface is of utmost importance. Processes at hidden interfaces are, however, difficult to analyze in detail and at relevant climatic conditions. This study has been divided in two parts, where the subject of Part I is the surface characterization by ATR-FTIR Kretschmann and IRRAS spectroscopy of aluminum coated with an amino-functional silane, and the interfacial analysis by ATR-FTIR Kretschmann after further application of an epoxy film. This second part describes the interaction between the coated sample and an electrolyte. The analysis is performed by integrated in situ ATR-FTIR Kretschmann and EIS, which requires model systems with evaporated metal films on an internal reflection element. Complementary analyses were also conducted on substrates in the absence of the metal film, and or in the absence of an epoxy top-coat, respectively. Changes in the interfacial region were observed and assigned to the water uptake including swelling of the epoxy, and the formation of aluminium oxidation and hydration products. Complementary studies allowed the distinction between water uptake in the silane film and the epoxy, respectively, as well as reformations of the siloxane network. © 2011 John Wiley & Sons, Ltd.

  • 495.
    Öhman, Maria
    et al.
    RISE, Swerea, Swerea KIMAB.
    Persson, Dan
    RISE, Swerea, Swerea KIMAB.
    Jacobsson, Dan
    RISE, Swerea, Swerea KIMAB.
    In situ studies of conversion coated zinc/polymer surfaces during exposure to corrosive conditions2011In: Progress in organic coatings, ISSN 0300-9440, E-ISSN 1873-331X, Vol. 70, no 1, p. 16-22Article in journal (Refereed)
    Abstract [en]

    This work investigates the hidden interface between a conversion-coated zinc surface and a polymer coating upon exposure to an electrolyte by simultaneous in situ ATR-FTIR and EIS. Various system properties were distinguished, such as the ingress of electrolyte constituents, and an active process of water-induced alterations of the conversion layer. The interface between a polymer film and a surface treated metal surface is of considerable fundamental and technical interest in many areas of application, and the results obtained open up the use of this method for a wide range of important applications. © 2010 Elsevier B.V. All rights reserved.

  • 496.
    Örnek, Cem
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB. KTH Royal Institute of Technology, Sweden.
    Liu, M.
    KTH Royal Institute of Technology, Sweden ; University of Science and Technology of Beijing, China.
    Pan, J.
    KTH Royal Institute of Technology, Sweden.
    Jin, Y.
    University of Science and Technology of Beijing, China.
    Leygraf, C.
    KTH Royal Institute of Technology, Sweden.
    Volta Potential Evolution of Intermetallics in Aluminum Alloy Microstructure Under Thin Aqueous Adlayers: A combined DFT and Experimental Study2018In: Topics in catalysis, ISSN 1022-5528, E-ISSN 1572-9028, Vol. 61, no 9-11, p. 1169-1182Article in journal (Refereed)
    Abstract [en]

    In this work, first-principle density functional theory (DFT) was used to calculate the work function and Volta potential differences between aluminum alloy matrix and two intermetallic phases (Mg2Si and Al2Cu) with varying surface terminations as a function of adhering monolayers (ML) of water. The calculated data were compared with experimental local Volta potential data obtained by the scanning Kelvin probe force microscopy (SKPFM) on a commercial aluminum alloy AA6063-T5 in atmospheric environments with varying relative humidity (RH). The calculations suggest that the surface termination has a major effect on the magnitude and polarity of the Volta potential of both intermetallic phases (IMP’s). The Volta potential difference between the IMP’s and the aluminum matrix decreases when the surface is gradually covered by water molecules, and may further change as a function of adhering ML’s of water. This can lead to nobility inversions of the IMP’s relative to the aluminum matrix. The measured Volta potential difference between both IMP’s and their neighboring matrix is dependent on RH. Natural oxidation in ambient indoor air for 2 months led to a nobility inversion of the IMP’s with respect to the aluminum matrix, with the intermetallics showing anodic nature already in dry condition. The anodic nature of Al2Cu remained with the introduction of RH, whereas Mg2Si became cathodic at high RH, presumably due to de-alloying of Mg and oxide dissolution. The DFT calculations predicted an anodic character of both IMP’s in reference to the oxidized aluminum matrix, being in good agreement with the SKPFM data. The DFT and SKPFM data were discussed in light of understanding localized corrosion of aluminum alloys under conditions akin to atmospheric exposure. 

  • 497.
    Örnek, Cem
    et al.
    KTH Royal Institute of Technology, Sweden.
    Långberg, Marie
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB. KTH Royal Institute of Technology, Sweden.
    Evertsson, Jonas
    Lund University, Sweden.
    Harlow, Gary
    Lund University, Sweden.
    Linpé, Weronica
    Lund University, Sweden.
    Rullik, Lisa
    Lund University, Sweden.
    Carlà, Francesco
    European Synchrotron Radiation Facility, France.
    Felici, Roberto
    SPINCNR, Italy.
    Bettini, Eleonora
    Sandvik Materials Technology, Sweden.
    Kivisäkk, Ulf
    Sandvik Materials Technology, Sweden.
    Lundgren, Edwin
    Lund University, Sweden.
    Pan, Jinshan
    KTH Royal Institute of Technology, Sweden.
    In-situ synchrotron GIXRD study of passive film evolution on duplex stainless steel in corrosive environment2018In: Corrosion Science, ISSN 0010-938X, E-ISSN 1879-0496, Vol. 141, p. 18-21Article in journal (Refereed)
    Abstract [en]

    This paper presents new findings about the passive film formed on super duplex stainless steel in ambient air and corrosive environments, studied by synchrotron grazing-incidence X-ray diffraction (GIXRD). The passive film, formed in air, was seen to be a nano-crystalline mixed-oxide. Electrochemical polarisation to the passive region in aqueous 1 M NaCl at room temperature resulted in an increase of the passive film thickness, preferential dissolution of Fe, and partial loss of crystallinity. After termination of polarization to the transpassive regime, reformation of the mixed-oxides was observed, showing a thicker, semi-crystalline, and more defective nature (more vacancies) with further new oxides/hydroxides.

  • 498.
    Örnek, Cem
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB. KTH Royal Institute of Technology, Sweden.
    Reccagni, Pierfranco
    University of Manchester, UK.
    Kivisäkk, Ulf
    AB Sandvik Materials Technology, Sweden.
    Bettini, Eleonora
    AB Sandvik Materials Technology, Sweden.
    Engelberg, Dirk L.
    University of Manchester, UK.
    Pan, Jinshan
    KTH Royal Institute of Technology, Sweden.
    Hydrogen embrittlement of super duplex stainless steel – Towards understanding the effects of microstructure and strain2018In: International journal of hydrogen energy, ISSN 0360-3199, E-ISSN 1879-3487, Vol. 43, no 27, p. 12543-12555Article in journal (Refereed)
    Abstract [en]

    The effects of austenite spacing, hydrogen charging, and applied tensile strain on the local Volta potential evolution and micro-deformation behaviour of grade 2507 (UNS S32750) super duplex stainless steel were studied. A novel in-situ methodological approach using Digital Image Correlation (DIC) and Scanning Kelvin Probe Force Microscopy (SKPFM) was employed. The microstructure with small austenite spacing showed load partitioning of tensile micro-strains to the austenite during elastic loading, with the ferrite then taking up most tensile strain at large plastic deformation. The opposite trend was seen when the microstructure was pre-charged with hydrogen, with more intense strain localisation formed due to local hydrogen hardening. The hydrogen-charged microstructure with large austenite spacing showed a contrasting micro-mechanical response, resulting in heterogeneous strain localisation with high strain intensities in both phases in the elastic regime. The austenite was hydrogen-hardened, whereas the ferrite became more strain-hardened. SKPFM measured Volta potentials revealed the development of local cathodic sites in the ferrite associated with hydrogen damage (blister), with anodic sites related to trapped hydrogen and/or micro voids in the microstructure with small austenite spacing. Discrete cathodic sites with large Volta potential variations across the ferrite were seen in the coarse-grained microstructure, indicating enhanced susceptibility to micro-galvanic activity. Microstructures with large austenite spacing were more susceptible to hydrogen embrittlement, related to the development of tensile strains in the ferrite.

  • 499.
    Östling, Henrik
    RISE, Swerea, Swerea KIMAB.
    Measurements of hardness and P, S and O levels in copper2013Report (Refereed)
    Abstract [sv]

    Copper intended for nuclear waste disposal has been studied to evaluate the hardness levels as well as the content of oxygen, sulphur and phosphorous. The materials studied were taken from previously published studies of creep development.

78910 451 - 499 of 499
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