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  • 1.
    Atwell, D.L.
    et al.
    Deakin University.
    Barnett, M.R.
    Deakin University.
    Hutchinson, Bevis
    RISE, Swerea, Swerea KIMAB.
    The effect of initial grain size and temperature on the tensile properties of magnesium alloy AZ31 sheet2012In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 549, p. s.1-6Article in journal (Refereed)
    Abstract [en]

    This research aimed to assemble and review data that are relevant to sheet metal formability of the magnesium alloy AZ31. Rolled sheets were processed to give four different grain sizes in the range from 2.9 to 47.1 μm. Similar basal textures were present in all these conditions. Tensile tests were carried out at various temperatures between 25 °C and 240 °C, with some additional tests also made below room temperature in dry ice. Results are presented and discussed relating to strength, ductility, strain rate sensitivity and anisotropy. An optimum grain size of about 7 μm applies for ductility over most of the temperature interval. Uniform elongation decreases steadily with increasing temperature whereas the post-necking and total elongation values increase markedly. Measurements of strength, anisotropy and strain rate sensitivity all indicate a significant role of grain boundary mediated deformation above room temperature. The plastic strain ratio, r, is high at room temperature but decreases considerably, especially for the fine grained conditions, at higher temperatures. Modifications to the active slip modes also occur over the same temperature interval but their effect on plasticity is probably less important than was previously believed. © 2012 Elsevier B.V.

  • 2.
    Fourlakidis, Vasilios
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, SWECAST.
    Dioszegi, Attila
    Jönköping University, Sweden.
    A generic model to predict the ultimate tensile strength in pearlitic lamellar graphite iron2014In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 618, p. 161-167Article in journal (Refereed)
    Abstract [en]

    Varying the carbon contents, chemical composition and solidification rate greatly influences the microstructural morphology in lamellar graphite iron resulting in large variations in material properties. Traditionally, ultimate tensile strength (UTS) is used as the main property for the characterisation of lamellar graphite iron alloys under static loads. The main models found in the literature for predicting UTS of pearlitic lamellar graphite iron are based on either regression analysis on experimental data or on modified Griffith or Hall-Petch equation.In pearlitic lamellar graphite iron the primary austenite transformed to pearlite reinforces the bulk material while the graphite flakes which are embedded in an iron matrix reduce the strength of the material. Nevertheless a dominant parameter which can be used to define the tensile strength is the characteristic distance between the pearlite grains defined as the maximum continuous defect size in the bulk material, which in this work is expressed by the newly introduced parameter the Diameter of Interdendritic Space. The model presented here covers the whole spectrum of carbon content from eutectic to hypoeutectic composition, solidified at different cooling rates typical for both thin and thick walled complex shaped castings.

  • 3.
    Hedström, Peter
    et al.
    KTH Royal Institute of Technology, Sweden.
    Huyan, Fei
    KTH Royal Institute of Technology, Sweden.
    Zhou, Jing
    KTH Royal Institute of Technology, Sweden.
    Wessman, Sten
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, KIMAB.
    Thuvander, Mattias
    Chalmers University of Technology, Sweden.
    Odqvist, Joakim
    KTH Royal Institute of Technology, Sweden.
    The 475°C embrittlement in Fe-20Cr and Fe-20Cr-X (X=Ni, Cu, Mn) alloys studied by mechanical testing and atom probe tomography2013In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 574, p. 123-129Article in journal (Refereed)
    Abstract [en]

    In the present work the 475 °C embrittlement in binary Fe-Cr and ternary Fe-Cr-X (X=Ni, Cu and Mn) alloys have been investigated. The mechanical properties were evaluated using microhardness and impact testing, and the structural evolution was evaluated using atom probe tomography (APT). The APT results after aging at 500 °C for 10. h clearly showed that both Ni and Mn accelerate the ferrite decomposition. No evident phase separation of either the Fe-20Cr or Fe-20Cr-1.5Cu samples was detected after 10. h of aging and thus no conclusions on the effect of Cu can be drawn. Cu clustering was however found in the Fe-20Cr-1.5Cu sample after 10. h aging at 500 °C. The mechanical property evolution was consistent with the structural evolution found from APT. Samples aged at 450 and 500 °C all showed increasing hardness and decreasing impact energy. The embrittlement was observed to take place mainly during the first 10. h of aging and it could primarily be attributed to phase separation, but also substitutional solute clustering and possibly carbon and nitrogen segregation may contribute in a negative way.

  • 4.
    Holmberg, Jonas
    et al.
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser. University West, Sweden.
    Steuwer, Axel
    Nelson Mandela Metropolitan University, South Africa.
    Stormvinter, Albin
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser.
    Kristoffersen, Hans
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser.
    Haakanen, Marja
    Stresstech OY, Finland.
    Berglund, Johan
    RISE - Research Institutes of Sweden (2017-2019), Materials and Production, IVF, Tillverkningsprocesser.
    Residual stress state in an induction hardened steel bar determined by synchrotron- and neutron diffraction compared to results from lab-XRD2016In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 667, p. 199-207Article in journal (Refereed)
    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.

  • 5.
    Iyer, Anand H.S
    et al.
    Chalmers University of Technology, Sweden.
    Stiller, Kristyna
    Chalmers University of Technology, Sweden.
    Leijon, Gunnar
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB.
    Andersson-Östling, Henrik C. M.
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB.
    Hörnqvist Colliander, Magnus
    Chalmers University of Technology, Sweden.
    Influence of dwell time on fatigue crack propagation in Alloy 718 laser welds2017In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 704, p. 440-447Article in journal (Refereed)
    Abstract [en]

    The introduction of welded assemblies in aerospace components aid in weight reduction, but also lead to an increased risk of defects. It is therefore important to analyze the high temperature crack growth resistance of such welds. The results from high temperature cyclic and dwell-fatigue testing of surface flawed Alloy 718 welds are presented here. An increasing temperature and application of a dwell time accelerate the crack growth and increase interaction with secondary phases. During cyclic loading at 550 °C, there is little interaction with the microstructure during transgranular propagation, but the application of dwell times results in a mixture of transgranular propagation and intergranular cracking of boundaries between different dendrites. At 650 °C, mixed intergranular and transgranular mode of crack growth is seen under both cyclic and dwell conditions. However, during dwell-fatigue the interfaces between the secondary arms of the same dendrite are also weakened, leading to an interfacial type of crack growth also in the intergranular parts.

  • 6.
    Karlsson, Joakim
    et al.
    RISE, SP – Sveriges Tekniska Forskningsinstitut. Arcam AB, Sweden.
    Sjögren, Torsten
    RISE, SP – Sveriges Tekniska Forskningsinstitut.
    Snis, Anders
    Arcam AB, Sweden.
    Engqvist, Håkån
    Uppsala University, Sweden.
    Lausmaa, Jukka
    RISE, SP – Sveriges Tekniska Forskningsinstitut, SP Kemi Material och Ytor.
    Digital image correlation analysis of local strain fields on Ti6Al4V manufactured by electron beam melting2014In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 618, p. 456-461Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing, or 3D-printing as it is often called, build parts in a layer-by-layer fashion. A common concern, regardless of the specific additive manufacturing technique used, is the risk of inadequate fusion between the adjacent layers which in turn may cause inferior mechanical properties. In this work, the local strain properties of titanium parts produced by Electron Beam Melting (EBM®) were studied in order to gain information about the quality of fusion of the stock powder material used in the process. By using Digital Image Correlation (DIC) the strain fields in the individual layers were analyzed, as well as the global strain behavior of the bulk material. The results show that fully solid titanium parts manufactured by EBM are homogenous and do not experience local deformation behavior, neither on local nor on a global level.

  • 7.
    Martin Vilardell, Anna
    et al.
    Karlstad University, Sweden.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Materials and Production.
    Åsberg, M.
    Karlstad University, Sweden.
    Dahl-Jendelin, Anton
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Krakhmalev, P.
    Karlstad University, Sweden.
    Oikonomou, C.
    Uddeholms AB, Sweden.
    Hatami, Sepehr
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Evaluation of post-treatments of novel hot-work tool steel manufactured by laser powder bed fusion for aluminum die casting applications2021In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 800, article id 140305Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing is a good alternative to conventional methods for the production of near net shape geometries with high geometric complexity shorter lead times, being a good option for the manufacturing of dies for die casting process. In this research, a novel hot-work tool steel for aluminum die casting applications manufactured by laser powder bed fusion was investigated. As-built and stress-relieved (AS-B + SR) state was established and used as the reference condition, and subsequent post-treatments were added and compared to the reference condition. Test parts were evaluated using tensile, impact, hardness and thermal fatigue testing. Compared to the reference condition, heat treatment (HT), significantly increased the hardness, yield and ultimate tensile strengths of the material, due to the obtained tempered martensite microstructure. Hot isostatic pressing (HIP) prior to HT significantly increased the impact toughness and ductility, and slightly increased the yield and ultimate tensile strength values compared to the HT condition. The addition of nitriding treatment after HT, without intermedium HIP step, resulted in the highest surface hardness and lowest impact toughness. Thermal fatigue was mostly affected by the hardness and the softening of the material during the thermal fatigue testing. Results showed that a high surface hardness resulted in a higher thermal fatigue crack nucleation, meanwhile conditions with a high softening during thermal fatigue performance resulted in a higher crack propagation.

  • 8.
    Moverare, J.J.
    et al.
    Linköping University.
    Leijon, Gunnar
    RISE, Swerea, Swerea KIMAB.
    Brodin, H.
    Linköping University.
    Palmert, F.
    Siemens Industrial Turbomachinery AB.
    Effect of SO2 and water vapour on the low-cycle fatigue properties of nickel-base superalloys at elevated temperature2013In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 564, p. 107-115Article in journal (Refereed)
    Abstract [en]

    In this study the effect of SO2+water vapour on strain controlled low cycle fatigue resistance of three different nickel based superalloys has been studied at 450°C and 550°C. A negative effect was found on both the crack initiation and crack propagation process. The effect increases with increasing temperature and is likely to be influenced by both the chemical composition and the grain size of the material. In general the negative effect decreases with decreasing strain range even if this means that the total exposure time increases. This is explained by the importance of the protective oxide scale on the specimen surface, which is more likely to crack when the strain range increases. When the oxide scale cracks, preferably at the grain boundaries, oxidation can proceed into the material, causing preferable crack initiation sites and reduced fatigue resistance. © 2012 Elsevier B.V.

  • 9.
    Neikter, M.
    et al.
    University West, Sweden.
    Bhaskar, P.
    University West, Sweden.
    Singh, S.
    Osaka University, Japan.
    Kadoi, K.
    Osaka University, Japan.
    Lyphout, Christophe
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes.
    Svahn, F.
    GKN Aerospace Sweden AB, Sweden.
    Pederson, R.
    University West, Sweden.
    Tensile properties of laser powder bed fusion built JBK-75 austenitic stainless steel2023In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 874, article id 144911Article in journal (Refereed)
    Abstract [en]

    Laser powder bed fusion (PBF-LB) is an additive manufacturing (AM) process that has several advantages to conventional manufacturing, such as near net-shaping capabilities and reduced material wastage. To be able to manufacture a novel material, however, one needs to first optimize the process parameters, to decrease porosity content as low as possible. Therefore, in this work the process parameters of PBF-LB built JBK-75 austenitic stainless steel, and its influence on porosity, microstructure, and hardness have been investigated. The least amount of porosity was found by using 132 W laser power, 750 mm/s scan speed, layer thickness 30 μm, and 0.12 mm hatch distance. These process parameters were then used to manufacture material for tensile testing, to investigate the tensile properties of PBF-LB built JBK-75 and potential anisotropic behavior. Hot isostatic pressing (HIP) was also performed in two sets of samples, to investigate the effect of pore closure on the tensile properties. The ultimate tensile strength (UTS) for the un-HIPed specimens was 1180 (horizontally built) and 1110 (vertically built) MPa. For the HIPed specimens, it was 1160 (horizontally built) and 1100 (vertically built) MPa. The anisotropic presence was explained by the presence of texture, with a multiple of random distribution (MRD) up to 4.34 for the {001} planes, and defects. 

  • 10.
    Pettersson, Niklas
    et al.
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB.
    Frisk, Karin
    RISE - Research Institutes of Sweden, Swerea, Swerea KIMAB.
    Fluch, Rainer
    Böhler Edelstahl Gmbh, Austria.
    Experimental and computational study of nitride precipitation in a CrMnN austenitic stainless steel2017In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 684, p. 435-441Article in journal (Refereed)
    Abstract [en]

    The austenitic CrMnN stainless steels are high-strength, tough, and non-magnetic, and are used in oil field applications. The steels have high alloying contents, and precipitation of Cr-nitrides and/or intermetallic phases can occur when cooling through the temperature region 950–700 °C. The nitride precipitates appear in the grain boundaries but can be difficult to observe in the microstructure due to their small size. However, there is an effect of precipitation on corrosion and impact strength and a modelling approach to predict precipitation is valuable for alloy and process development. In the present work precipitation simulations were applied to a CrMnN steel composition, and coupled to experimental investigations after heat treatments at 700 and 800 °C. The early stages, with short heat-treatment times, were studied. The simulations were performed using TC-PRISMA, a software for calculation of multiphase precipitation kinetics, using multicomponent nucleation and growth models. Dedicated thermodynamic and kinetic databases were used for the simulations. The main precipitate was identified by experiments and simulations to be the Cr2N nitride, and the precipitation during isothermal heat treatments was investigated. Isothermal precipitation diagrams are simulated, and the influence of precipitation kinetics on toughness is discussed.

  • 11.
    Pettersson, Niklas
    et al.
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Wessman, Sten
    RISE - Research Institutes of Sweden, Materials and Production, KIMAB.
    Thuvander, Mattias
    Chalmers University of Technology, Sweden.
    Hedström, Peter
    KTH Royal Institute of Technology, Sweden.
    Odqvist, Joachim
    KTH Royal Institute of Technology, Sweden.
    Pettersson, Rachel F. A.
    The Swedish Steel Producers' Association, Sweden.
    Hertzman, Staffan
    Outokumpu Stainless Research Foundation, Sweden.
    Nanostructure evolution and mechanical property changes during aging of a super duplex stainless steel at 300°C2015In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 647, p. 241-248Article in journal (Refereed)
    Abstract [en]

    The nanostructure evolution and the corresponding changes in mechanical properties of a super duplex stainless steel 2507 (UNS S32750) during aging at 300. °C up to 12,000. h have been investigated. Microstructural studies using transmission electron microscopy and atom probe tomography show that subtle Cr concentration fluctuations develop during aging. The amplitude of the concentration fluctuations is proportional to the hardness of the ferrite phase, and it is also proportional to the decrease in room temperature impact toughness during aging. The fracture behaviour of the alloy changes gradually from ductile to cleavage fracture, upon aging. The cracks were found to propagate through the ferrite phase, partly along deformation twin interfaces, and delamination between the austenite and ferrite phases was observed.

  • 12.
    Sandström, Rolf
    et al.
    RISE, Swerea, KIMAB. KTH Royal Institute of Technology, Sweden.
    Wu, Rui
    RISE, Swerea, KIMAB.
    Hagström, Joacim
    RISE, Swerea, KIMAB.
    Grain boundary sliding in copper and its relation to cavity formation during creep2016In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 651, p. 259-268Article in journal (Refereed)
    Abstract [en]

    The nucleation of creep cavities, which control the creep ductility is assumed to take place by grain boundary sliding. To determine the grain boundary sliding rate at longer testing times than previously available in the literature, two creep tests have been performed at constant loading rate at 125. °C for oxygen free copper with phosphorus (Cu-OFP). The tests were interrupted after certain strains and the amount of grain boundary sliding (GBS) was measured on flat polished surfaces. The observed amount of GBS per unit strain was 20 to 65 μm. This is of the same order of magnitude as for published tensile tests (Pettersson, 150 and 200. °C) and short time creep tests (Ayensu and Langdon, 400-600. °C). The amount of GBS was modelled based on previously performed FEM investigations. For conditions corresponding to the experiments a value of 52. μm was obtained.A model by Lim for cavity nucleation at junctions between cell and grain boundaries has been adapted to oxygen free pure copper Cu-OF and Cu-OFP. The results show that the gain in free energy at cavity nucleation is much larger for Cu-OF than for Cu-OFP implying that Cu-OF is much more prone to cavity formation. The modelled difference in free energy gain is sufficient to quantitatively explain the much higher creep ductility in Cu-OFP than in Cu-OF.

  • 13.
    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.

  • 14.
    Yuan, M.
    et al.
    Chalmers University of Technology, Sweden.
    Cao, Y.
    Chalmers University of Technology, Sweden; Central South University, China.
    Karamchedu, S.
    Uddeholms AB, Sweden.
    Hosseini, Seyed
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Yao, Y.
    Chalmers University of Technology, Sweden.
    Berglund, Johan
    RISE Research Institutes of Sweden, Materials and Production, Manufacturing Processes. Chalmers University of Technology, Sweden.
    Liu, L.
    Central South University, China.
    Nyborg, L.
    Chalmers University of Technology, Sweden.
    Characteristics of a modified H13 hot-work tool steel fabricated by means of laser beam powder bed fusion2022In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 831, article id 142322Article in journal (Refereed)
    Abstract [en]

    In the present study, a modified H13 hot-work tool steel (M-H13) was fabricated by laser beam powder bed fusion (LB-PBF). The effect of two types of post processing, direct tempering from as-built condition (DT) and conventional quenching followed by tempering (QT), on the microstructure and mechanical properties was evaluated. The typical microstructure in QT condition was tempered martensite with carbides along lath boundaries. In DT condition, melt pool boundaries and cellular structure from as-built condition were still observed. While comparable tensile properties and hardness were obtained, DT samples exhibited significantly lower impact toughness compared to QT samples. This was attributed to the difference in work hardening ability and strain rate sensitivity originating from different microstructures obtained under these two heat treatment conditions. The study was also focused on the softening behavior and the correlation with the microstructure of the two post treatments at the elevated temperatures. It was found that the DT samples showed lower thermal softening compared to QT samples. The evolution of carbides was discussed based on the microanalysis results and the JMatPro simulation. © 2021 The Authors

  • 15.
    Åsberg, M.
    et al.
    Karlstad University, Sweden.
    Fredriksson, G.
    Karlstad University, Sweden.
    Hatami, Seperh
    RISE - Research Institutes of Sweden, Swerea, Swerea IVF.
    Fredriksson, W.
    Bodycote Hot Isostatic Pressing AB, Sweden.
    Krakhmalev, P.
    Karlstad University, Sweden.
    Influence of post treatment on microstructure, porosity and mechanical properties of additive manufactured H13 tool steel2019In: Materials Science & Engineering: A, ISSN 0921-5093, E-ISSN 1873-4936, Vol. 742, p. 584-589Article in journal (Refereed)
    Abstract [en]

    Additive manufacturing (AM) is an attractive manufacturing technology in tooling applications. It provides unique opportunities to manufacture tools with complex shapes, containing inner channels for conformal cooling. In this investigation, H13, a widely used tool steel, was manufactured using a laser powder bed fusion method. Microstructure, tensile mechanical properties, hardness, and porosity of the AM H13 after stress relieve (SR), standard hardening and tempering (SR + HT), and hot isostatic pressing (SR + HIP + HT) were investigated. It was found that the microstructure of directly solidified colonies of prior austenite, which is typical for AM, disappeared after austenitizing at the hardening heat treatment. In specimens SR + HT and SR + HIP + HT, a microstructure similar to the conventional but finer was observed. Electron microscopy showed that SR and SR + HT specimens contained lack of fusion, and spherical gas porosity, which resulted in remarkable scatter in the observed elongation to break values. Application of HIP resulted in the highest strength values, higher than those observed for conventional H13 heat treated in the same way. The conclusion is that HIP promotes reduction of porosity and lack of fusion defects and can be efficiently used to improve the mechanical properties of AM H13 tool steel.

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