Effect of Preheat Treatment on Microstructure and Properties of a Gear Steel for High‐Temperature Carburizing

An, Xizhong; Tian, Yong; Wang, Haojie; Wang, Zhaodong

doi:10.1002/srin.202000180

Cited by 9 publications

(6 citation statements)

References 31 publications

(25 reference statements)

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“…The martensite start (Ms) temperature in the steel is closely related to the content of Cs and alloying elements in the steel. [ 23 ] After solution treatment, the Ms temperature in the steel is lower, which is further decreased in the surface layer of the steel due to the high carbon content after minor carburizing. After tempering, due to the precipitation of Cs, the Ms temperature of the inside and outside of the surface layer will increase.…”

Section: Discussionmentioning

confidence: 99%

Effect of Minor Carburizing on Microstructure and Mechanical Properties of M50 Bearing Steel

Shen

Wei

et al. 2022

steel research int.

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Herein, by using scanning electron microscopy, transmission electron microscope, X‐ray diffraction, residual stress analyzer, and mechanical‐property tests, the effect of minor carburizing on the microstructure and mechanical properties of M50 steel is studied. It is shown in the results that after minor carburizing, the austenite content in the surface layer of the quenched M50 steel increases, while the martensite content and the hardness decrease. After tempering, the retained austenite in the surface layer is transformed into martensite, and a large amount of uniformly distributed carbides are precipitated. The hardness of the surface layer increases to exceed that of the core region in the steel. After the minor carburizing, there is a carbon concentration gradient between the surface layer and the core region of the M50 steel, which influences the phase transformation behavior and the residual stress state in the surface layer during the tempering process. Minor carburizing increases the rotational bending fatigue limit of the steel by 16.7% and improves the tensile strength, yield strength, and impact absorption energy of the steel.

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Section: Discussionmentioning

confidence: 99%

Effect of Minor Carburizing on Microstructure and Mechanical Properties of M50 Bearing Steel

Shen

Wei

et al. 2022

steel research int.

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“…Coal-cutting machine is an important mechanical equipment to improve coal supply efficiency and promote industrial development. The heavy-duty gear is the core component of coal-cutting machines [1], which requires carburizing and other treatment methods to obtain a highly wear-resistant and toughened surface hardened layer [2][3][4]. The materials used for low-speed and heavyduty gears of coal-cutting machines in China are mainly high-alloy chromium-nickel steels such as 18Cr2Ni4WA and 20Cr2Ni4.…”

Section: Introductionmentioning

confidence: 99%

Effects of High Temperature Tempering on Microstructure and Hardness Distribution on 18Cr2Ni4WA Alloy Steel Heavy-duty Gears: Numerical Simulation and Experiments

Yuan

Yang

Jiang

et al. 2023

J. Phys.: Conf. Ser.

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In the present work, simulations of gas carburizing heat treatment of heavy-duty gears on a coal-cutting machine fabricated by a 18Cr2Ni4WA alloy steel were carried out by using a finite element method software. The physical property database of the 18Cr2Ni4WA alloy steel was constructed in the software. The effects of the high temperature tempering process on the microstructure and hardness distributions were simulated and studied. The hardness distribution results obtained by simulation are in good agreement with the experimental results, which verifies the accuracy of the simulation. The evolution of the volume fractions of the austenite, martensite, and bainite microstructure after high temperature tempering was simulated, while the change of the retained austenite varying with the number of high temperature tempering was studied. The results show that with the increase of the number of high-temperature tempering, the content of retained austenite in the gear decreases, and it could reduce the surface carbon concentration. The hardness variation, calculated by the Maynier equation through secondary development, is shown to be governed by the joint influence of carbon concentration and microstructure distribution. The hardness distribution from the surface layer to the core is 62HRC-32HRC after the heat treatment process with twice high tempering, which meets the needs of the practical application of the gears.

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“…[1][2][3][4][5][6][7][8] The gear heat treatment process often encounters severe banded structures, which can result in uneven carburized layer depth and hardness, leading to issues such as mismatched gear steel structure and hardness. [9][10][11][12][13][14] Therefore, it is necessary to eliminate the banded structure in gear steel. [15][16][17][18][19] The fundamental reason for the formation of banded microstructures is the dendritic segregation that occurs during the solidification process of the cast slab.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Cooling Rate on the Banded Structure of 20CrMnTi Gear Steel Based on C Diffusion and Partitioning Analysis

Zhao,

Chen,

et al. 2023

steel research int.

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This study, through experimental analysis and numerical calculations, not only identifies the critical cooling rate for eliminating banded structures in 20CrMnTi gear steel but also analyzes the impact of cooling rate on banded structures, including the mechanisms related to element distribution and interface migration. The results indicate that the fundamental cause of banded structure formation is the presence of chemical segregation bands, and increasing the cooling rate leads to a reduction in the grade of ferrite/pearlite banded structures, with a critical cooling rate of 0.55 °C s−1. Bainite and martensite banded structures are observed in samples cooled at rates of 3 and 5.8 °C s−1, respectively. As the cooling rate increases from 0.07 to 1 °C s−1. The ferrite phase transformation time in the solute‐poor zone is shortened from 171 to 12 s within the ferrite phase transformation temperature difference (Δ) between the poor and rich solute zones. The concentration difference of C on both sides of the α/γ phase interface increases from 0.350 mass% to 0.431 mass%, and the diffusion distance of C decreases from 34.38 to 7.57 μm. When the diffusion distance of C is less than half of the width of the solute‐rich banding (12.5 μm), the ferrite banded structure disappears.

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Effect of Preheat Treatment on Microstructure and Properties of a Gear Steel for High‐Temperature Carburizing

Cited by 9 publications

References 31 publications

Effect of Minor Carburizing on Microstructure and Mechanical Properties of M50 Bearing Steel

Effect of Minor Carburizing on Microstructure and Mechanical Properties of M50 Bearing Steel

Effects of High Temperature Tempering on Microstructure and Hardness Distribution on 18Cr2Ni4WA Alloy Steel Heavy-duty Gears: Numerical Simulation and Experiments

The Effect of Cooling Rate on the Banded Structure of 20CrMnTi Gear Steel Based on C Diffusion and Partitioning Analysis

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