Evolution of the microstructure and mechanical properties of powder metallurgical high-speed steel S390 after heat treatment

Peng, Hanlin; Hu, Ling; Li, Liejun; Zhang, Liyun; Zhang, Xianglin

doi:10.1016/j.jallcom.2017.12.264

Cited by 46 publications

(35 citation statements)

References 26 publications

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“…This indicates that the EBM process temperature was above the martensite starting temperature of 351°C. [28] Upon build completion, the samples were cooled slowly within the EBM build chamber. The relative density of as-EBM samples was measured using Archimedes drainage method.…”

Section: B Ebm Sample Fabricationmentioning

confidence: 99%

“…As a consequence, such a large lattice expansion cannot be simply attributed to residual stresses due to rapid cooling. According to References 24,28,35, and 36 that cover a wide range of high-speed steels, only three phases with the fcc crystal structure should be expected; they are retained austenite, MC, and M 6 C carbides. The MC carbide has a lattice parameter of a = 4.13 Å (ICDD-PDF 89-5055), while a = 11.09 Å for M 6 C carbide (ICDD-PDF 78-1990).…”

Section: Matrix Phase Identificationmentioning

confidence: 99%

“…[19,44,45] For the present PM S390 high-speed tool steel, the highest HRC hardness value obtainable for the hot-isostatic-pressed (HIP) + austenitized + tempered condition as reported in the literature so far is between 62 and 68 HRC. [20,28,46] By contrast, for the EBM S390 steel, even without the post-processing heat treatment, the as-EBM microstructure already comes with the good hardness value of 65 HRC (Table III). The average transverse rupture strength for the as-EBM S390 steel achieves a high value of~2500 MPa, that is higher than that offered by the conventional means.…”

Section: Microstructure and Mechanical Propertymentioning

confidence: 99%

See 2 more Smart Citations

Rapid Solidification Microstructure and Carbide Precipitation Behavior in Electron Beam Melted High-Speed Steel

Jin

Gao

Peng

et al. 2020

Metall Mater Trans A

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The solidified microstructure and carbide precipitation behavior in an S390 high-speed steel processed by electron beam melting (EBM) have been fully characterized. The as-EBM microstructure consists of discontinuous network of very fine primary carbides dispersed in auto-tempered martensite matrix together with a limited amount of retained austenite. The carbide network consists of M 2 C/M 6 C and MC carbides. Both the columnar and near-equiaxed grain structures were found in as-EBM microstructure and the presence of inter-dendritic eutectic carbides assisted in revealing the dendritic solidification nature. The top-layer microstructure observation confirmed that the columnar dendritic structured grains were located adjacent to the micro-melt pool boundary, indicating an epitaxial growth with the average growth direction parallel to the maximum thermal gradient. At the center of the micro-melt pool, the near-equiaxed grains were developed by dendritic growth parallel to the beam traveling direction. The carbide decomposition was revealed by scanning transmission electron microscopy and confirmed by transmission Kikuchi diffraction. The MC carbides (rich in V followed by W) nucleated at the interface between M 2 C (W, Fe, Mo, and Co in the order of significance) and the matrix and then grew from the outside inward, but their nucleation might occur from the M 2 C carbide itself. The thermal effect induced by the adjacent scan lines seems to trigger a solid-state phase transformation of MC fi M 2 C + c-Fe. The elemental migration was theoretically calculated and compared with the experimental results. The high hardness of~65 HRC and good transverse rupture strength of~2500 MPa in as-EBM S390 means that EBM processing can be used to fabricate highly alloyed tool steels. With the help of the post-processing heat treatment, the best Rockwell hardness of 73.1±0.2 HRC and transverse rupture strength of 3012±34 MPa can be obtained.

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Section: B Ebm Sample Fabricationmentioning

confidence: 99%

Section: Matrix Phase Identificationmentioning

confidence: 99%

Section: Microstructure and Mechanical Propertymentioning

confidence: 99%

See 1 more Smart Citation

Rapid Solidification Microstructure and Carbide Precipitation Behavior in Electron Beam Melted High-Speed Steel

Jin

Gao

Peng

et al. 2020

Metall Mater Trans A

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“…The types of carbides [26], change of carbide precipitation and structure after cryogenic treatment [27,28], and precipitation model of carbides during heat treatment have been studied [29,30,31]. Scholars have also analyzed the heat treatment behavior of PM S390 steel [32]. M. Godec et al observed the carbide transformation in M42 annealing process by in-situ EBSD [3].…”

Section: Introductionmentioning

confidence: 99%

Effect of Tempering Conditions on Secondary Hardening of Carbides and Retained Austenite in Spray-Formed M42 High-Speed Steel

Liu

Tian

et al. 2019

Materials

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In this study, the effect of tempering conditions on microstructure, grain size, and carbide phase compositions of spray-formed high-speed steel after quenching at 1180 °C was studied. The influence of carbide phase, size of carbides, and retained austenite content on secondary hardening of the steel was analyzed by field emission scanning electron microscope (FESEM), transmission electron microscope (TEM), electron backscattered diffraction (EBSD), and differential scanning calorimetry (DSC); the hardness, microhardness of carbide, and bending strength were tested. The results show that M3C, M6C, M7C3, and MC carbides may precipitate at different tempering temperatures and the transformation of the retained austenite can be controlled by tempering. The phase composition of carbides, microstructure, and retained austenite content strongly influences the performance characteristics of M42 high-speed steel after tempering. In contrast, the secondary carbides produced by tempering thrice at 540 °C are mainly M6C carbides rich in W and Mo elements, and the content of retained austenite is effectively reduced. At this stage, the Rockwell hardness reaches 67.2 HRC, bending strength reaches 3115 MPa, and the properties and microstructure are optimal.

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“…With excellent mechanical properties at high temperatures, Fe-Co-Cr-Mo-W-V-C alloy has been used to replace traditional industrial cutting tool materials. Owing to the addition of molybdenum, chromium, tungsten, and vanadium to around 15 wt.%, a large amount of carbides precipitate in the microstructure during solidification and cooling, which give the cutting tools higher hardness, better wear resistance, and strength [1,2,3]. Although the cobalt (about 8 wt.%) in the alloy is not a carbide-forming element, it contributes to increasing dislocation density, retarding dislocation recovery, and improving high-temperature properties [4,5].…”

Section: Introductionmentioning

confidence: 99%

Gleeble-Simulated and Semi-Industrial Studies on the Microstructure Evolution of Fe-Co-Cr-Mo-W-V-C Alloy during Hot Deformation

Luo

Guo

et al. 2018

Materials

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Fe-Co-Cr-Mo-W-V-C alloy is one of the most important materials for manufacturing drills, dies, and other cutting tools owing to its excellent hardness. However, it is prone to cracking due to its poor hot ductility during continuous hot working processes. In this investigation, the microstructure characteristics and carbide transformations of the alloy in as-cast and wrought states are studied, respectively. Microstructural observation and first-principles calculation were conducted on the research of types and mechanical properties of carbides. The results reveal that carbides in as-cast Fe-Co-Cr-Mo-W-V-C alloy are mainly Mo2C, VC, and Cr-rich carbides (Cr7C3 and Cr23C6). The carbides in wrought Fe-Co-Cr-Mo-W-V-C alloy consist of Fe2Mo4C, VC, Cr7C3, and a small amount of retained Mo2C. For these carbides, Cr7C3 presents the maximum bulk modulus and B/G values of 316.6 GPa and 2.48, indicating Cr7C3 has the strongest ability to resist the external force and crack initiation. VC presents the maximum shear modulus and Yong’s modulus values of 187.3 GPa and 465.3 GPa, which means VC can be considered as a potential hard material. Hot isothermal compression tests were performed using a Gleeble-3500 device to simulate the flow behavior of the alloy during hot deformation. As-cast specimens were uniaxially compressed to a 70% height reduction over the temperature range of 1323–1423 K and strain rates of 0.05–1 s−1. A constitutive equation was established to characterize the relationship of peak true stress, strain rate, and deformation temperature of the alloy. The calculated results were in a good agreement with the experimental data. In order to study the texture evolution, the microstructures of the deformed specimens were observed, and an optimal deformation temperature was selected. Using the laboratorial optimal temperature (1373 K) in forging of an industrial billet resulted in uniform grains, with the largest size of 17 µm, surrounded by homogenous spherical carbides.

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Evolution of the microstructure and mechanical properties of powder metallurgical high-speed steel S390 after heat treatment

Cited by 46 publications

References 26 publications

Rapid Solidification Microstructure and Carbide Precipitation Behavior in Electron Beam Melted High-Speed Steel

Rapid Solidification Microstructure and Carbide Precipitation Behavior in Electron Beam Melted High-Speed Steel

Effect of Tempering Conditions on Secondary Hardening of Carbides and Retained Austenite in Spray-Formed M42 High-Speed Steel

Gleeble-Simulated and Semi-Industrial Studies on the Microstructure Evolution of Fe-Co-Cr-Mo-W-V-C Alloy during Hot Deformation

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