Tempering Hardness Prediction Model of New TBM Disc Cutter Material 7Cr5Mo2MnVSi Steel

doi:10.3901/JME.2025.12.083

Abstract

Abstract: 7Cr5Mo2MnVSi steel has secondary hardening phenomenon during tempering process, which makes it have higher tempering hardness and has become one of the new wear-resistant disc cutter ring materials. However, the traditional tempering hardness model cannot accurately predict the secondary hardening hardness of 7Cr5Mo2MnVSi steel. In order to establish a prediction model for the tempering hardness of 7Cr5Mo2MnVSi steel, a tempering hardness model of 7Cr5Mo2MnVSi steel was proposed according to the tempering kinetic model and Orowan mechanism. The effects of martensitic restitution softening and carbide precipitation strengthening on the steel hardness were comprehensively considered in this model. The tempering hardness model predicting results show that the size of carbide particles significantly affects the tempering hardness of 7Cr5Mo2MnVSi steel. When the tempering temperature is below 400 ℃, the size of carbide particles unchanged. The tempering hardness of 7Cr5Mo2MnVSi steel is dominated by the recovery softening of martensite; When the tempering temperature is between 400 ℃ and 580 ℃, the size of carbide particles first decreases and then increases with tempering temperature. The secondary hardening hardness peak of 62.2 HRC appears at the temperature around 520 ℃, which is consistent with the test results. The correlations coefficient between the prediction results of the proposed model and the test results of 7Cr5Mo2MnVSi steel under different tempering processes is 0.98，while that of between the traditional model and the test results is 0.45. Compared to the traditional model, new model can accurately predict the secondary hardening effect of tempering in 7Cr5Mo2MnVSi steel.

Key words: TBM disc cutter material, Steel 7Cr5Mo2MnVSi, tempering process, hardness prediction model

CLC Number:

TG115

SHANG Yong, JIA Xibei, SUN Jingdong, JIANG Haifeng, LI Guang, SUN Chaoyang. Tempering Hardness Prediction Model of New TBM Disc Cutter Material 7Cr5Mo2MnVSi Steel[J]. Journal of Mechanical Engineering, 2025, 61(12): 83-92.

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