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  • 1.
    Akbari, Saeed
    et al.
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Holmberg, Jonas
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Andersson, Dag
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Mishra, Madhav
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Brinkfeldt, Klas
    RISE Research Institutes of Sweden, Digitala system, Smart hårdvara.
    Packaging Induced Stresses in Embedded and Molded GaN Power Electronics Components2023Inngår i: Int. Conf. Therm., Mech. Multi-Phys. Simul. Exp. Microelectron. Microsyst., EuroSimE, Institute of Electrical and Electronics Engineers Inc. , 2023Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Residual stresses created during the packaging process can adversely affect the reliability of electronics components. We used incremental hole-drilling method, following the ASTM E 837-20 standard, to measure packaging induced residual stresses in discrete packages of power electronics components. For this purpose, we bonded a strain gauge on the surface of a Gallium Nitride (GaN) power component, drilled a hole through the thickness of the component in several incremental steps, recorded the relaxed strain data on the sample surface using the strain gauge, and finally calculated the residual stresses from the measured strain data. The recorded strains and the residual stresses are related by the compliance coefficients. For the hole drilling method in the isotropic materials, the compliance coefficients are calculated from the analytical solutions, and available in the ASTM standard. But for the orthotropic multilayered components typically found in microelectronics assemblies, numerical solutions are necessary. We developed a subroutine in ANSYS APDL to calculate the compliance coefficients of the hole drilling test in the molded and embedded power electronics components. This can extend the capability of the hole drilling method to determine residual stresses in more complex layered structures found in electronics. 

  • 2.
    Berglund, Johan
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser. Chalmers University of Technology, Sweden.
    Holmberg, Jonas
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Wärmefjord, Kristina
    Chalmers University of Technology, Sweden.
    Söderberg, Rikard
    Chalmers University of Technology, Sweden.
    Detailed evaluation of topographical effects of Hirtisation post-processing on electron beam powder bed fusion (PBF-EB) manufactured Ti-6Al-4V component2024Inngår i: Precision engineering, ISSN 0141-6359, E-ISSN 1873-2372, Vol. 85, s. 319-327Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Metal additive manufacturing surface topographies are complex and challenging to characterise due to e.g. steep local slopes, re-entrant features, varying reflectivity and features of interest in vastly different scale ranges. Nevertheless, average height parameters such as Ra or Sa are commonly used as sole parameters for characterisation. In this paper, a novel method for selecting relevant parameters for evaluation is proposed and demonstrated using a case study where the smoothing effects after three processing steps of the electro chemical post-process Hirtisation of a metal AM surface are quantified. The method uses a combination of conventional areal texture parameters, multiscale analysis and statistics and can be used to efficiently achieve a detailed and more relevant surface topography characterisation. It was found that the three process steps have different effects on the surface topography regarding the types and sizes of features that were affected. In total, Sdq was reduced by 97 %, S5v was reduced by 81 % and Sa was reduced by 78 %. A surface texture with much lower average roughness, less deep pits and less steep slopes was produced, which is expected to be beneficial for improved fatigue properties.

  • 3.
    Götelid, Sareh
    et al.
    Swerim AB, Sweden.
    Ma, Taoran
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Lyphout, Christophe
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Vang, Jesper
    Swerim AB, Sweden.
    Stålnacke, Emil
    Swerim AB, Sweden.
    Holmberg, Jonas
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Strondl, Annika
    Swerim AB, Sweden.
    Effect of post-processing on microstructure and mechanical properties of Alloy 718 fabricated using powder bed fusion additive manufacturing processes2021Inngår i: Rapid prototyping journal, ISSN 1355-2546, E-ISSN 1758-7670, Vol. 27, nr 9, s. 1617-1632Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Purpose: This study aims to investigate additive manufacturing of nickel-based superalloy IN718 made by powder bed fusion processes: powder bed fusion laser beam (PBF-LB) and powder bed fusion electron beam (PBF-EB). Design/methodology/approach: This work has focused on the influence of building methods and post-fabrication processes on the final part properties, including microstructure, surface quality, residual stresses and mechanical properties. Findings: PBF-LB produced a much smoother surface. Blasting and shot peening (SP) reduced the roughness even more but did not affect the PBF-EB surface finish as much. As-printed PBF-EB parts have low residual stresses in all directions, whereas it was much higher for PBF-LB. However, heat treatment removed the stresses and SP created compressive stresses for samples from both PBF processes. The standard Arcam process parameter for PBF-EB for IN718 is not fully optimized, which leads to porosity and inferior mechanical properties. However, impact toughness after hot isostatic pressing was surprisingly high. Originality/value: The two processes gave different results and also responses to post-treatments, which could be of advantage or disadvantage for different applications. Suggestions for improving the properties of parts produced by each method are presented.

  • 4.
    Holmberg, Jonas
    RISE Research Institues of Sweden, Sweden.
    High volumetric machining strategies for superalloy gasturbine components: Comparing conventional and nonconventional machining methods for efficient manufacturing2020Doktoravhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    There is a strong industrial driving force to find alternative manufacturing technologies in order to make the production of aero engine components of superalloys even more efficient than it is today. Introducing new and nonconventional machining technologies, as well as enhanced utilisation of today's high volumetric manufacturing, allows taking a leap to increase the material removal rate and the productivity. However, the final goal is to meet there quirements set for today's machined surfaces.The objective with the present work has been performed to show how the conventional, Milling, and the non-conventional machining methods, Abrasive Water Jet Machining, AWJM, Laser Beam Machining, LBM, and Electrical Discharge Machining, EDM, affect the surface integrity. This knowledge can beused to define and optimise different manufacturing alternatives for existing orfuture production.The results show that it is possible to use the rough milling to a greater extent if the impact on residuals stresses and deformation is used when determine the machining allowance. This could have a great impact on the productivity. However, further improvement of the productivity requires an alternative method. For this reason, EDM and AWJM was evaluated and shown to be suitable alternatives to today's manufacturing methods, but both methods require post processing. The results showed that a combination of two post processes is required for addressing issues with residue, topography and residual stresses.The most promising and effective manufacturing strategy would be EDM or AWJM for rough machining followed by post processing either by finish millingor post processing by means of High-Pressure Water Jet Cleaning and shot peening. If EDM and AWJM are to be considered as finish machining operations, further development of the two methods are required.

  • 5.
    Holmberg, Jonas
    RISE Research Institutes of Sweden, Sweden.
    Surface integrity on post processed alloy 718 after nonconventional machining2018Licentiatavhandling, monografi (Annet vitenskapelig)
    Abstract [en]

    There is a strong industrial driving force to find alternative production technologies in order to make the production of aero engine components of superalloys even more efficient than it is today. Introducing new and nonconventional machining technologies allows taking a giant leap to increase the material removal rate and thereby drastically increase the productivity. However, the end result is to meet the requirements set for today's machined surfaces.The present work has been dedicated to improving the knowledge of how the non-conventional machining methods Abrasive Water Jet Machining, AWJM, Laser Beam Machining, LBM, and Electrical Discharge Machining, EDM, affect the surface integrity. The aim has been to understand how the surface integrity could be altered to an acceptable level. The results of this work have shown that both EDM and AWJM are two possible candidates but EDM is the better alternative; mainly due to the method's ability to machine complex geometries. It has further been shown that both methods require post processing in order to clean the surface and to improve the topography and for the case of EDM ageneration of compressive residual stresses are also needed.Three cold working post processes have been evaluated in order to attain this: shot peening, grit blasting and high pressure water jet cleaning, HPWJC. There sults showed that a combination of two post processes is required in order to reach the specified level of surface integrity in terms of cleaning and generating compressive residual stresses and low surface roughness. The method of high pressure water jet cleaning was the most effective method for removing the EDM wire residuals, and shot peening generated the highest compressive residual stresses as well as improved the surface topography.To summarise: the most promising production flow alternative using nonconventional machining would be EDM followed by post processing using HPWJC and shot peening.

  • 6.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Brohede, Ulrika
    Swerim AB, Sweden.
    Åkerfeldt, Pia
    Luleå university of Technolgy, Sweden.
    Sandell, Viktor
    Luleå university of Technology, Sweden.
    Rashid, Amir
    KTH Royal institute of Technology, Sweden.
    Zhao, Xiaoyu
    KTH Royal institute of Technology, Sweden.
    Dadbakhsh, Sasan
    KTH Royal institute of Technology, Sweden.
    Fischer, Marie
    Chalmers university of Technology, Sweden.
    Hryha, Eduard
    Chalmers university of Technology, Sweden.
    Wiklund, Urban
    Uppsala university, Sweden.
    Hassila, Carl Johan Karlsson
    Uppsala university, Sweden.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Machining of additively manufactured alloy 718 in as-built and heat-treated condition: surface integrity and cutting tool wear2023Inngår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 130, nr 3-4, s. 1823-1842Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Additive manufacturing (AM) using powder bed fusion is becoming a mature technology that offers great possibilities and design freedom for manufacturing of near net shape components. However, for many gas turbine and aerospace applications, machining is still required, which motivates further research on the machinability and work piece integrity of additive-manufactured superalloys. In this work, turning tests have been performed on components made with both Powder Bed Fusion for Laser Beam (PBF-LB) and Electron Beam (PBF-EB) in as-built and heat-treated conditions. The two AM processes and the respective heat-treatments have generated different microstructural features that have a great impact on both the tool wear and the work piece surface integrity. The results show that the PBF-EB components have relatively lower geometrical accuracy, a rough surface topography, a coarse microstructure with hard precipitates and low residual stresses after printing. Turning of the PBF-EB material results in high cutting tool wear, which induces moderate tensile surface stresses that are balanced by deep compressive stresses and a superficial deformed surface that is greater for the heat-treated material. In comparison, the PBF-LB components have a higher geometrical accuracy, a relatively smooth topography and a fine microstructure, but with high tensile stresses after printing. Machining of PBF-LB material resulted in higher tool wear for the heat-treated material, increase of 49%, and significantly higher tensile surface stresses followed by shallower compressive stresses below the surface compared to the PBF-EB materials, but with no superficially deformed surface. It is further observed an 87% higher tool wear for PBF-EB in as-built condition and 43% in the heat-treated condition compared to the PBF-LB material. These results show that the selection of cutting tools and cutting settings are critical, which requires the development of suitable machining parameters that are designed for the microstructure of the material.

    Fulltekst (pdf)
    fulltext
  • 7.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Stormvinter, Albin
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Andersson, Pär
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Lundin, Per
    Ludin Stress Service AB, Sweden.
    Influence of Local Electropolishing Conditions on Ferritic–Pearlitic Steel on X-Ray Diffraction Residual Stress Profiling2024Inngår i: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 33, s. 3682-Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Layer removal with electropolishing is a well-established method when measuring residual stress profiles with lab-XRD. This is done to measure the depth impact from processes such as shot peening, heat treatment, or machining. Electropolishing is used to minimize the influence on the inherent residual stresses of the material during layer removal, performed successively in incremental steps to specific depths followed by measurement. Great control of the material removal is critical for the measured stresses at each depth. Therefore, the selection of size of the measurement spot and electropolishing parameters is essential. The main objective in this work is to investigate how different electrolytes and electropolishing equipment affect the resulting surface roughness, geometry, microstructure, and consequently the measured residual stress. A second objective has been to establish a methodology of assessing the acquired electropolished depth. The aim has been to get a better understanding of the influence of the layer removal method on the accuracy of the acquired depth. Evaluation has been done by electropolishing one ground and one shot peened sample of a low-alloy carbon steel, grade 1.1730, with different methods. The results showed a difference in stresses depending on the electrolyte used where the perchloric acid had better ability to retain the stresses compared to the saturated salt. Electropolishing with saturated salt is fast and results in evenly distributed material removal but has high surface roughness, which is due to a difference in electropolishing of the two phases, ferrite, and pearlite. Perchloric acid electropolishing is slower but generates a smooth surface as both ferrite and pearlite have the same material removal rates but may cause an increased material removal for the center of the electropolished area. In this work, it is suggested to use perchloric acid electropolishing for the final layer removal step. © 2023, The Author(s).

  • 8.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Beno, Tomas
    University West, Sweden.
    Evaluation of surface integrity after high energy machining with EDM, laser beam machining and abrasive water jet machining of alloy 7182019Inngår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 100, nr 5-8, s. 1575-1591Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Development of future aero engine components based on new design strategies utilising topological optimisation and additive manufacturing has in the past years become a reality. This allows for designs that involve geometries of “free form” surfaces and material combinations that could be difficult to machine using conventional milling. Hence, alternative manufacturing routes using non-conventional high energy methods are interesting to explore. In this investigation, the three high energy machining methods abrasive water jet machining (AWJM), electrical discharge machining (EDM) and laser beam machining (LBM) have been compared in terms of surface integrity to the reference, a ball nosed end milled surface. The results showed great influence on the surface integrity from the different machining methods. It was concluded that AWJM resulted in the highest quality regarding surface integrity properties with compressive residual stresses in the surface region and a low surface roughness with texture from the abrasive erosion. Further, it was shown that EDM resulted in shallow tensile residual stresses in the surface and an isotropic surface texture with higher surface roughness. However, even though both methods could be considered as possible alternatives to conventional milling they require post processing. The reason is that the surfaces need to be cleaned from either abrasive medium from AWJM or recast layer from EDM. It was further concluded that LBM should not be considered as an alternative in this case due to the deep detrimental impact from the machining process. © 2018, The Author(s).

  • 9.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Sweden.
    Klason, Anki
    Hanza Mechanics Sweden AB, Sweden.
    Persson, Roger
    Hanza Mechanics Sweden AB, Sweden.
    Milling or grinding for manufacturing of an Alloy 718 gas turbine component?: – A comparison of surface integrity and productivity2024Inngår i: Procedia CIRP, E-ISSN 2212-8271, Vol. 123, s. 7-12Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Milling is traditionally the most used machining method when manufacturing complex gas turbine components. In particular those made from nickel-based superalloys. However, for larger free form surfaces, grinding may be an efficient alternative that could be used throughout the complete manufacturing route, from roughing to finishing. Hence, in this work the two processing methods has been compared in regard to surface integrity and productivity. Machining tests have been performed on case plates of heat-treated Alloy 718 using best practise setting for roughing and finishing with grinding and milling. The surface integrity of the work pieces was evaluated regarding surface topography, residual stresses, and deformation. This comparison showed that the main advantage with grinding is the ability to switch between roughing and finishing by just altering the depth of cut. Further, grinding offers lower surface roughness, compressive residual stresses, and significantly lower degree of deformation. From a productivity perspective, deep grinding may offer high material removal rates and ability to machine several work pieces in the same setup. However, grinding is limited to simpler free form geometries and may result in minor surface damages and abrasive surface residue. For selection of machining strategy, advantages and drawbacks shown in this work need to be considered for the application at hand in respect to productivity, surface integrity and requirements on fatigue life.

    Fulltekst (pdf)
    fulltext
  • 10.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden, Material och produktion, IVF. University West, Sweden.
    Hammerberg, Peter
    Chalmers University of Technology, Sweden.
    Lundin, Per
    Schlumpf Scandinavia AB, Sweden.
    Olavison, Jari
    Volvo Group Trucks Operations, Sweden.
    Hardness depth assessment of induction hardened steel by a comparative approach using Barkhausen Noise and Ultrasonic signals2019Inngår i: Proceedings of ICBM13, 2019Konferansepaper (Annet vitenskapelig)
    Abstract [en]

    A major challenge in automotive industry when producing heat treated engine parts is achievement of necessary material properties for a given component to withstand loads during its use. Critical properties involve correct microstructure and hardening depth which is essential to verify from manufacturing.

    Today this is solely done by destructive testing where manufactured parts are sectioned to smaller pieces and the properties is verified relative the operational window of the process. For the case of camshafts this is necessary every time the production is reset from one type to another or other planned or un-planned interruptions. The verification process is very costly, since production stands still.

    The need for non-destructive alternatives is therefore obvious and prior investigations has shown great potential in both the Barkhausen noise (BN) and Ultrasonic testing (UT) methods. Recent research has also advanced the analysing methodology of the response signal for sub-surface microstructural characterization and case depth measurements. BN is well known of its sensitivity to microstructure and UT is also known to be effective for material characterization. One major difference between the two technologies is the sensitivity range (analysing depth) under the surface of the material to be characterized. Traditional BN is only effective within few tenths of millimetres from the surface while UT is sensitive to both surface and sub-surface characteristics of the material depending on the configuration.

    The major motive in this investigation has been to compare the two methods and to investigate if a combination of these methods could be used for assessment of the hardening depth of induction hardened steels for the depth interval 2-7 mm. This is a typical depth range when manufacturing induction hardened cam shafts within the heavy automotive industry.

    In the present investigation cylindrical steel specimens of grade C45 was induction hardened to generate different hardness depths. The heat treatment was performed in an induction hardening equipment by alternating the scanning speed and power. The produced specimens had hardness depth in the range 2-7 mm and was evaluated with by BN and UT measurements, independently, followed by destructive verification of the material properties.

    The results show a potential for both BN and UT to measure the hardening depth down to 4 mm. It was further shown that several BN parameters correlate with the hardening depth indicating that a combination of different parameters may be used for assessment using a triangulation approach.

  • 11.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Hammersberg, Peter
    Chalmers University of Technology, Sweden.
    Lundin, Per
    Lundin Stress Service AB, Sweden.
    Olavison, Jari
    Volvo Group Trucks Operations, Sweden.
    Predictive Modeling of Induction-Hardened Depth Based on the Barkhausen Noise Signal2023Inngår i: Micromachines, E-ISSN 2072-666X, Vol. 14, nr 1Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    A non-destructive verification method was explored in this work using the Barkhausen noise (BN) method for induction hardening depth measurements. The motive was to investigate the correlation between the hardness depth, microstructure, and the Barkhausen noise signal for an induction hardening process. Steel samples of grade C45 were induction-hardened to generate different hardness depths. Two sets of samples were produced in two different induction hardening equipment for generating the model and verification. The produced samples were evaluated by BN measurements followed by destructive verification of the material properties. The results show great potential for the several BN parameters, especially the magnetic voltage sweep slope signal, which has strong correlation with the hardening depth to depth of 4.5 mm. These results were further used to develop a multivariate predictive model to assess the hardness depth to 7 mm, which was validated on an additional dataset that was holdout from the model training.

  • 12.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Lundin, Per
    Stresstech OY, Finland.
    Olavisson, Jari
    Volvo Powertrain AB, Sweden.
    Sevim, Solmaz
    Bodycote, Sweden.
    Non destructive testing of surface characteristics after nitrocarburizing of three different steel grades2017Konferansepaper (Annet vitenskapelig)
  • 13.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF. University West, Sweden.
    Palosaari, Mikko
    Stresstech OY, Finland.
    Hosseini, Seyed
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Larjosuo, Henri
    Stresstech OY, Finland.
    Andersson, Pär
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF. RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Round Robin Study on Residual Stresses Using X-RayDiffraction for Shot-Peened Tool Steel Specimens2018Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Residual stress measurements using x-ray diffraction is a well established methodused within the industrial and academic community to verify the performance of differentprocesses for metallic materials. The measurement gives an absolute value of the stress statewhich can be used to design and optimize the process route to induce beneficial compressiveresidual stresses and avoid detrimental tensile stresses. Investigating the uncertainty andaccuracy of the measurement system, operator and the material is therefore of high relevanceboth from an industrial and scientific point of view. Round robin testing is an important way toquantify the uncertainties that could affect the quality of the measured results and hence how aprocess is optimized and tuned. Such an investigation allows the operator to understand andreduce variations. Current round robin test includes results from five different laboratories usingcomparable equipments located in Sweden, Finland, Germany and United States. This workfocuses on five shot-peened tool steel specimens produced with identical process settings.Additionally, an investigation of the repeatability of the system, influence of the operator,variations within the specimen, and the long time stability of the specimens has been measured.

  • 14.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Rodri­guez Prieto, Juan Manuel
    Luleå University of Technology, Sweden.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Sveboda, Ales
    Luleå University of Technology, Sweden.
    Jonsén, Pär
    Luleå University of Technology, Sweden.
    Experimental and PFEM-simulations of residual stresses from turning tests of a cylindrical Ti-6Al-4V shaft2018Inngår i: Procedia CIRP, ISSN 2212-8271, E-ISSN 2212-8271, Vol. 71, s. 144-149Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alloy Ti-6Al-4V is a frequently used material in aero space applications due the high strength and low weight. This material is however often considered as a difficult to machine alloy due to several material properties such as the inherent characteristics of high hot hardness and strength which is causing an increased deformation of the cutting tool during machining. The thermal properties also cause a low thermal diffusion from locally high temperatures in the cutting zone that allows for reaction to the tool material resulting in increased tool wear. Predicting the behavior of machining of this alloy is therefore essential when selecting machining tools or machining strategies. If the surface integrity is predicted, the influence of different machining parameters could be studied using Particle Finite Element (PFEM)-simulations. In this investigation the influence from cutting speed and feed during turning on the residual stresses has been measured using x-ray diffraction and compared to PFEM-simulations. The results showed that cutting speed and feed have great impact on the residual stress state. The measured cutting force showed a strong correlation especially to the cutting feed. The microstructure, observed in SEM, showed highly deformed grains at the surface from the impact of the turning operation and the full width half maximum from the XDR measurements distinguish a clear impact from different cutting speed and feed which differed most for the higher feed rate. The experimental measurements of the residual stresses and the PFEM simulations did however not correlate. The surface stresses as well as the sign of the residuals stresses differed which might be due to the material model used and the assumption of using a Coulomb friction model that might not represent the cutting conditions in the investigated case. © 2018 Elsevier B.V. All rights reserved.

    Fulltekst (pdf)
    fulltext
  • 15.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF, Tillverkningsprocesser. University West, Sweden.
    Steuwer, Axel
    Nelson Mandela Metropolitan University, South Africa.
    Stormvinter, Albin
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF, Tillverkningsprocesser.
    Kristoffersen, Hans
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF, Tillverkningsprocesser.
    Haakanen, Marja
    Stresstech OY, Finland.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF, Tillverkningsprocesser.
    Residual stress state in an induction hardened steel bar determined by synchrotron- and neutron diffraction compared to results from lab-XRD2016Inngår i: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 667, s. 199-207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Induction hardening is a relatively rapid heat treatment method to increase mechanical properties of steel components. However, results from FE-simulation of the induction hardening process show that a tensile stress peak will build up in the transition zone in order to balance the high compressive stresses close to the surface. This tensile stress peak is located in the transition zone between the hardened zone and the core material. The main objective with this investigation has been to non-destructively validate the residual stress state throughout an induction hardened component. Thereby, allowing to experimentally confirming the existence and magnitude of the tensile stress peak arising from rapid heat treatment. For this purpose a cylindrical steel bar of grade C45 was induction hardened and characterised regarding the microstructure, hardness, hardening depth and residual stresses. This investigation shows that a combined measurement with synchrotron/neutron diffraction is well suited to non-destructively measure the strains through the steel bar of a diameter of 20 mm and thereby making it possible to calculate the residual stress profile. The result verified the high compressive stresses at the surface which rapidly changes to tensile stresses in the transition zone resulting in a large tensile stress peak. Measured stresses by conventional lab-XRD showed however that at depths below 1.5 mm the stresses were lower compared to the synchrotron and neutron data. This is believed to be an effect of stress relaxation from the layer removal. The FE-simulation predicts the depth of the tensile stress peak well but exaggerates the magnitude compared to the measured results by synchrotron/neutron measurements. This is an important knowledge when designing the component and the heat treatment process since this tensile stress peak will have great impact on the mechanical properties of the final component.

  • 16.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Wendel, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Stormvinter, Albin
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Progressive Induction Hardening: Measurement and Alteration of Residual Stresses2024Inngår i: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Progressive induction hardening is an in-line steel heat treatment method commonly used to surface harden powertrain components. It produces a martensitic case layer with a sharp transition zone to the base material. This rapid process will induce large residual stresses, where a compressive state in the case layer will shift to a tensile state in the transition zone. For fatigue performance, it is important to quantify the magnitude and distribution of these stresses, and moreover how they depend on material and processing parameters. In this work, x-ray diffraction in combination with a layer removal method is used for efficient and robust quantification of the subsurface stress state, which combines electropolishing with either turning or milling. Characterization is done on C45E steel samples that were progressively induction hardened using either a fast or slow (27.5 or 5 mm/s, respectively) scanning speed. The results show that although the hardening procedures will meet arbitrary requirements on surface hardness, case depth and microstructure, the subsurface tensile stress peak magnitude is doubled when using a fast scanning speed. However, the near-surface compressive residual stresses are comparable. In addition, the subsurface tensile residual stress peak is compared with the on-surface tensile stresses in the fade-out zone.

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  • 17.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Wretland, Anders
    GKN Aerospace Engine Systems AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Abrasive Water Jet Milling as An Efficient Manufacturing Method for Superalloy Gas Turbine Components2022Inngår i: Journal of Manufacturing and Materials Processing, ISSN 2504-4494, Vol. 6, nr 5, artikkel-id 124Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In order to improve efficiency when manufacturing gas turbine components, alternative machining techniques need to be explored. In this work, abrasive water jet (AWJ) machining by milling has been investigated as an alternative to traditional milling. Various test campaigns have been conducted to show different aspects of using AWJ milling for the machining of superalloys, such as alloy 718. The test campaigns span from studies of individual AWJ-milled tracks, multi-pass tracks, and the machining of larger components and features with complex geometry. In regard to material removal rates, these studies show that AWJ milling is able to compete with traditional semi/finish milling but may not reach as high an MRR as rough milling when machining in alloy 718. However, AWJ milling requires post-processing which decreases the total MRR. It has been shown that a strong advantage with AWJ milling is to manufacture difficult geometries such as narrow radii, holes, or sharp transitions with kept material removal rates and low impact on the surface integrity of the cut surface. Additionally, abrasive water jet machining (AWJM) offers a range of machining possibilities as it can alter between cutting through and milling. The surface integrity of the AWJM surface is also advantageous as it introduces compressive residual stress but may require post-processing to meet similar surface roughness levels as traditional milling and to remove unwanted AWJM particles from the machined surface. © 2022 by the authors.

  • 18.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF. University Wes, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Grit Blasting for Removal of Recast Layer from EDM Process on Inconel 718 Shaft: An Evaluation of Surface Integrity2016Inngår i: Journal of materials engineering and performance (Print), ISSN 1059-9495, E-ISSN 1544-1024, Vol. 25, nr 12, s. 5540-5550Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The heat generated during EDM melts the work material and thereby allows large amounts to be removed, but an unfavorable surface of a recast layer (RCL) will also be created. This layer has entirely different properties compared to the bulk. Hence, it is of great interest to efficiently remove this layer and to verify that it has been removed. The main objective of this work has been to study the efficiency of grit blasting for removal of RCL on an EDM aero space shaft. Additionally, x-ray fluorescence (XRF) has been evaluated as a nondestructive measurement to determine RCL presence. The results show that the grit-blasting processing parameters have strong influence on the ability to remove RCL and at the same time introduce beneficial compressive stresses even after short exposure time. Longer exposure will remove the RCL from the surface but also increase the risk that a larger amount of the blasting medium will get stuck into the surface. This investigation shows that a short exposure time in combination with a short grit-blasting nozzle distance is the most preferable process setting. It was further found that handheld XRF equipment can be used as a nondestructive measurement in order to evaluate the amount of RCL present on an EDM surface. This was realized by analyzing the residual elements from the EDM wire.

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  • 19.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Beno, Tomas
    University West, Sweden.
    A detailed investigation of residual stresses after milling Inconel 718 using typical production parameters for assessment of affected depth2020Inngår i: Materials Today Communications, ISSN 2352-4928, Vol. 24, artikkel-id 100958Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Production of superalloy gas turbine parts involves time consuming milling operations typically performed in a sequence from rough to finish milling. Rough milling using ceramic inserts allows high removal rates but causes severe sub-surface impact. A relatively large allowance is therefore left for subsequent cemented carbide milling. With increased knowledge of the affected depth it will be possible to reduce the machining allowance and increase efficiency of the manufacturing process. Milling Inconel 718 using typical production parameters has been investigated using new and worn ceramic and cemented carbide inserts. Residual stresses in a milled slot were measured by x-ray diffraction. Stresses were measured laterally across the slot and below the surface, to study the depth affected by milling. The most important result from this work is the development of a framework concerning how to evaluate the affected depth for a milling operation. The evaluation of a single milled slot shows great potential for determining the optimum allowance for machining. Our results show that the residual stresses are greatly affected by the ceramic and cemented carbide milling; both regarding depth as well as distribution across the milled slot. It has been shown that it is important to consider that the stresses across a milled slot are the highest in the center of the slot and gradually decrease toward the edges. Different inserts, ceramic and cemented carbide, and tool wear, alter how the stresses are distributed across the slot and the affected depth.

  • 20.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Beno, Tomas
    University West, Sweden.
    Selection of milling strategy based on surface integrity investigations of highly deformed Alloy 718 after ceramic and cemented carbide milling2020Inngår i: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 58, s. 193-207Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    High speed milling with ceramic indexable inserts is a current practice for manufacturing of gas turbine components in superalloys since it allows for high material removal rates. Ceramic milling is used for rough milling, which is followed by cemented carbide semi- and finish milling. The tool motion play an important role on the resulting surface integrity. The machining strategy of up or down milling will induce different degree of residual stresses and deformations. Increased knowledge of selecting the machining strategy with lowest impact will promote improved productivity by using ceramic milling to a greater extent based on the affected depth. The main objective in this work has been to correlate the residual stresses and deformations to promote a greater utilization of ceramic milling while still producing surfaces with acceptable properties. Prior investigations have shown that ceramic milling induce very high tensile stresses in the surface, exceeding the material's nominal yield strength. A second objective has been to explain these stress levels by thorough investigations of the deformation after milling. In this study, milling tests with new and worn ceramic and cemented carbide inserts have been performed in Alloy 718. The topography, residual stresses, deformation and hardness have been investigated for up, centre and down milling. Residual stress measurements were performed using X-ray diffraction, followed by evaluation of hardness and deformation, using hardness testing, light optical microscopy as well as electron back scattering diffraction (EBSD). These results have been used to determine an appropriate milling strategy based on lowest possible impact in respect to residual stresses and deformation. The results show a high degree of deformation after milling that differs for the up, centre and down milling. Based on these results, it is shown that up milling is preferable for new inserts but as the inserts wear out, down milling becomes more suitable since a lower degree of deformation and residual stress impact was observed. EBSD and hardness testing showed that the milling, especially ceramic milling, caused severe deformation of the surfaces resulting in grain refinement to a nano-crystalline level. This is most likely the explanation for the prevalence of the high tensile stresses without distorting or causing failure. © 2020 The Authors

  • 21.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Beno, Tomas
    University West, Sweden.
    Surface integrity after post processing of EDM processed Inconel 718 shaft2018Inngår i: The International Journal of Advanced Manufacturing Technology, ISSN 0268-3768, E-ISSN 1433-3015, Vol. 95, nr 5-8, s. 2325-2337Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Electrical discharge machining (EDM) is considered as an efficient alternative to conventional material removal concepts that allows for much higher material removal rates. However, EDM generates unwanted features such as re-cast layer (RCL), tensile residual stresses and a rough surface. In order to recover the surface integrity, different post processes has been compared: high-pressure water jet (HPWJ), grit blasting (GB) and shot peening (SP). Surface integrity has been evaluated regarding microstructure, residual stresses, chemical content and surface roughness. The results showed that a combination of two post processes is required in order to restore an EDM processed surface of discontinuous islands of RCL. HPWJ was superior for removing RCL closely followed by grit blasting. However, grit blasting showed embedded grit blasting abrasive into the surface. Regarding surface roughness, it was shown that both grit blasting and HPWJ caused a roughening of the surface topography while shot peening generates a comparably smoother surface. All three post processes showed compressive residual stresses in the surface where shot peening generated the highest amplitude and penetration depths. However, the microstructure close to the surface revealed that shot peening had generated cracks parallel to the surface. The results strongly state how important it is to evaluate the surface at each of the different subsequent process steps in order to avoid initiation of cracks. © 2017 The Author(s)

  • 22.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Wretland, Anders
    GKN Aerospace Sweden AB, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Beno, Tomas
    University West, Sweden.
    Karlsson, Anton
    Tooltec Trestad AB, Sweden.
    Surface integrity investigation to determine rough milling effects for assessment of machining allowance for subsequent finish milling of alloy 7182021Inngår i: Journal of Manufacturing and Materials Processing, ISSN 2504-4494, Vol. 5, nr 2, artikkel-id 48Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    The planned material volume to be removed from a blank to create the final shape of a part is commonly referred to as allowance. Determination of machining allowance is essential and has a great impact on productivity. The objective of the present work is to use a case study to investigate how a prior rough milling operation affects the finish machined surface and, after that, to use this knowledge to design a methodology for how to assess the machining allowance for subsequent milling operations based on residual stresses. Subsequent milling operations were performed to study the final surface integrity across a milled slot. This was done by rough ceramic milling followed by finish milling in seven subsequent steps. The results show that the up-, centre and down-milling induce different stresses and impact depths. Employing the developed methodology, the depth where the directional influence of the milling process diminishes has been shown to be a suitable minimum limit for the allowance. At this depth, the plastic flow causing severe deformation is not present anymore. It was shown that the centre of the milled slot has the deepest impact depth of 500 µm, up-milling caused an intermediate impact depth of 400 µm followed by down milling with an impact depth of 300 µm. With merged envelope profiles, it was shown that the effects from rough ceramic milling are gone after 3 finish milling passes, with a total depth of cut of 150 µm. © 2021 by the authors. 

  • 23.
    Holmberg, Jonas
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser. University West, Sweden.
    Wretland, Anders
    GKN Aerospace Engine System Sweden AB, Sweden.
    Hammersberg, Peter
    Chalmers University of Technology, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Suárez, Alfredo
    Tecnalia R&T, Spain.
    Beno, Tomas
    University West, Sweden.
    Surface integrity investigations for prediction of fatigue properties after machining of alloy 7182021Inngår i: International Journal of Fatigue, ISSN 0142-1123, E-ISSN 1879-3452, Vol. 144, artikkel-id 106059Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Fatigue performance is crucial for gas turbine components, and it is greatly affected by the manufacturing processes. Ability to predict the expected fatigue life of a component based on surface integrity has been the objective in this work, enabling new processing methods. Alloy 718 samples were prepared by different machining setups, evaluated in fatigue testing and surface integrity investigations. These results generated two predictive statistical multi-variate regression models. The fatigue correlated well with roughness, residual stresses and deformation. The two models showed great potential, which encourages further exploration to fine-tune the procedure for the particular case. © 2020 The Authors

  • 24.
    Hosseini, Seyed
    et al.
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser. Chalmers University of Technology, Sweden.
    Mallipeddi, D.
    Chalmers University of Technology, Sweden.
    Holmberg, Jonas
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Rännar, L. -E
    Mid Sweden University, Sweden.
    Koptyug, A.
    Mid Sweden University, Sweden.
    Sjöström, W.
    Mid Sweden University, Sweden.
    Krajnik, P.
    Chalmers University of Technology, Sweden.
    Klement, U.
    Chalmers University of Technology, Sweden.
    Comparison of machining performance of stainless steel 316L produced by selective laser melting and electron beam melting2022Inngår i: Procedia CIRP, Elsevier B.V. , 2022, s. 72-77Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Powder bed fusion processes based additively manufactured SS 316L components fall short of surface integrity requirements needed for optimal functional performance. Hence, machining is required to achieve dimensional accuracy and to enhance surface integrity characteristics. This research is focused on comparing the material removal performance of 316L produced by PBF-LB (laser) and PBF-EB (electron beam) in terms of tool wear and surface integrity. The results showed comparable surface topography and residual stress profiles. While the hardness profiles revealed work hardening at the surface where PBF-LB specimens being more susceptible to work hardening. The investigation also revealed differences in the progress of the tool wear when machining specimens produced with either PBF-LB or PBF-EB. .

  • 25.
    Jäger, Henrik
    et al.
    RISE., Swerea, KIMAB. University West, Sweden.
    Alagan, N. T.
    University West, Sweden.
    Holmberg, Jonas
    RISE., Swerea, IVF. University West, Sweden.
    Beno, T.
    University West, Sweden.
    Wretland, A.
    EDS Analysis of Flank Wear and Surface Integrity in Machining of Alloy 718 with Forced Coolant Application2016Inngår i: Procedia CIRP, Elsevier B.V. , 2016, s. 271-274Konferansepaper (Fagfellevurdert)
    Abstract [en]

    There has been extensive research on forced coolant application, usually known as high pressure coolant, in machining heat resistant super alloys. This technology has shown to improve the tool life, chip segmentation, surface integrity and reduce the temperature in the cutting zone. A number of studies have been done on hydraulic parameters of the coolant. This study has been focused on residues on the flank face of the insert and residual stress on the workpiece surface generated by regular and modified cutting inserts. To identify any residual elements, analysis were done by energy dispersive X-ray spectrometer, EDS, on regular as well as modified inserts in combination with forced coolant application on both rake and flank face. The investigations have shown that the temperature gradient in the insert has changed between the regular and modified cutting inserts and that the tool wear and surface roughness is significantly affected by the modified cutting tool. © 2016 The Authors.

  • 26.
    Kokkirala, Sahith
    et al.
    Chalmers University of Technology, Sweden.
    Holmberg, Jonas
    RISE Research Institutes of Sweden, Material och produktion, Tillverkningsprocesser.
    Klement, Uta
    Chalmers University of Technology, Sweden.
    Lundström, Roger
    AB SKF, Sweden.
    Iwasaki, H
    SUMITOMO ELECTRIC Hartmetall GmbH, Germany.
    Hosseini, Seyed
    Chalmers University of Technology, Sweden.
    Effect of cutting parameters on the generated surface integrity of hard-turned martensitic AISI 52100 bearing steel2022Inngår i: Procedia CIRP, Elsevier B.V. , 2022, s. 154-159Konferansepaper (Fagfellevurdert)
    Abstract [en]

    Hard turning offers improved manufacturing efficiency but requires great control of the cutting process to achieve the required machining-induced surface integrity with respect to residual stresses, surface topography, and near-surface microstructure. This research work is focused on studying the effect of the cutting speed, feed rate, depth of cut, chamfer angle, and coolant pressure on the surface integrity after hard turning of martensitic AISI 52100 steel. The results showed that the feed rate had a significant influence on the residual stresses and the surface topography. The discontinuous mechanically induced white layer was observed at high cutting speed and high chamfer angle with increased thickness. 

  • 27.
    Mahade, Satyapal
    et al.
    University West, Sweden.
    Ruelle, Celine
    ENSIL, France.
    Curry, Nicholas
    Treibacher Industrie AG, Austria.
    Holmberg, Jonas
    RISE - Research Institutes of Sweden, Material och produktion, IVF.
    Björklund, Stefan
    University West, Sweden.
    Markocsan, Nicholaie
    University West, Sweden.
    Nylén, Per
    University West, Sweden.
    Understanding the effect of material composition and microstructural design on the erosion behavior of plasma sprayed thermal barrier coatings2019Inngår i: Applied Surface Science, ISSN 0169-4332, E-ISSN 1873-5584, Vol. 488, s. 170-184Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    In this work, three different TBC compositions comprising of yttria partially stabilized zirconia (8YSZ), yttria fully stabilized zirconia (48YSZ) and gadolinium zirconate (GZ) respectively, were processed by suspension plasma spray (SPS) to obtain columnar microstructured TBCs. Additionally, for comparison, lamellar microstructured, 7YSZ TBC was deposited by air plasma spray (APS) process. SEM analysis was carried out to investigate the microstructure and white light interferometry was used to evaluate the surface morphology of the as-sprayed TBCs. Porosity measurements were made using water intrusion and image analysis methods and it was observed that the SPS-YSZ and APS-YSZ TBCs showed higher porosity content than SPS-GZ and SPS-48YSZ. The as-sprayed TBC variations (APS-YSZ, SPS-YSZ, SPS-GZ, and SPS-48YSZ) were subjected to erosion test. Results indicate that the erosion resistance of APS-YSZ TBC was inferior to the SPS-YSZ, SPS-GZ and SPS-48YSZ TBCs respectively. Among the SPS processed TBCs, SPS-YSZ showed the highest erosion resistance whereas the SPS-48YSZ showed the lowest erosion resistance. SEM analysis of the eroded TBCs (cross section and surface morphology) was performed to gain further insights on their erosion behavior. Based on the erosion results and post erosion SEM analysis, erosion mechanisms for splat like microstructured APS TBC and columnar microstructured SPS TBCs were proposed. The findings from this work provide new insights on the erosion mechanisms of columnar microstructured TBCs and lamellar microstructured TBCs deposited by plasma spray.

  • 28.
    Suárez, A.
    et al.
    Tecnalia R&I, Spain.
    Veiga, F.
    Tecnalia R&I, Spain.
    Polvorosa, R.
    University of the Basque Country, Spain.
    Artaza, T.
    Tecnalia R&I, Spain.
    Holmberg, Jonas
    RISE - Research Institutes of Sweden, Material och produktion, IVF. University West, Sweden.
    de Lacalle, L. N. L.
    University of the Basque Country, Spain.
    Wretland, A.
    GKN Aerospace Engine Systems AB, Sweden.
    Surface integrity and fatigue of non-conventional machined Alloy 7182019Inngår i: Journal of Manufacturing Processes, ISSN 1526-6125, Vol. 48, s. 44-50Artikkel i tidsskrift (Fagfellevurdert)
    Abstract [en]

    Alloy 718 is a high-strength, corrosion-resistant nickel chromium-based superalloy frequently used for applications, such as aerospace, marine, nuclear reactor and chemical industries, due to its outstanding inherent properties such as high strength and corrosion resistance at high temperatures together with good creep behaviour. Although, the use of conventional manufacturing processes is prevalent for their use on Alloy 718, alternative manufacturing technologies are gaining importance. This work compares the effects of alternative manufacturing processes, such as Abrasive water jet (AWJ), Wire Electrical Discharge Machining (WEDM) and ultrasound vibration assisted milling (UVAM) with conventional milling during the manufacture of Alloy 718 parts. Surface integrity, hardness, residual stress and fatigue strength obtained from these machining processes have been examined for cutting alloy 718. Results show that both residual stresses and surface roughness are correlated with fatigue strength. UVAM results shown an improvement on the surface integrity of the final workpiece. AWJ and WEDM show poorer results, further work on post-process technologies or process condition selection must be carry out to establish them as an alternative in Alloy 718 cutting operations.

  • 29.
    Wadman, Boel
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Ottosson, Peter
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Holmberg, Jonas
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Ingemarsson, Lars-Olof
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Sagström, Elisabeth
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Time-dependent residual stress and geometry analysis of UHSS deep drawn components,2013Inngår i: Proceedings of International Deep Drawing Research Group Conference, Zurich, Switzerland, June 2-5., 2013Konferansepaper (Annet vitenskapelig)
  • 30.
    Werke, Mats
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Wretland, Anders
    GKN Aerospace AB, Sweden.
    Ottosson, Peter
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Holmberg, Jonas
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Machens, Michael
    RISE - Research Institutes of Sweden (2017-2019), Material och produktion, IVF.
    Semere, Daniel
    KTH Royal Institute of Technology, Sweden.
    Geometric distortion analysis using a combination of the contour method and machining simulation2018Inngår i: Procedia CIRP, 2018, s. 1481-1486Konferansepaper (Fagfellevurdert)
    Abstract [en]

    During machining the material removal releases residual stresses introduced by previous process steps. This causes geometric machining distortions and thereby high rejection rates and costs. By simulating the process chain it is possible to predict this type of distortions. However, this requires advanced material models and accurate process- and material data for the individual processes. In order to simplify the modelling efforts a methodology that combines the contour method with machining simulation is proposed. The methodology is validated for an aerospace component using deep layer removal X-ray diffraction and CMM measurements. The methodology will improve possibilities to reduce machining distortions. © 2018 The Authors.

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