Effect of heat treatment on microstructure and mechanical properties of 42CrMo steel picks

doi:10.13251/j.issn.0254-6051.2023.06.001

Abstract

Abstract: Taking foreign similar products as references, many kinds of duplex-phase and induction quenching treatments were applied to 42CrMo steel picks. Hardness, impact absorbed energy, microstructure and fracture morphology of the 42CrMo steel picks after different heat treatments were investigated. The effects of heat treatments on microstructure and mechanical properties were analyzed. The results show that after duplex-phase heat treatment process, the microstructure includes lower bainite/martensite (LB/M) and a small amount of retained austenite (RA), grain size is smaller and LB has better comprehensive mechanical properties, and impact absorbed energy is higher than that after quenching and low temperature tempering (Q-T) process. Local induction quenching process not only has the highest impact absorbed energy and the hardness of pick head, but also realizes the axial hardness distribution of hard head and soft handle of the pick, which is beneficial to extending the service life. The fracture morphology of the specimen treated by Q-T process shows cleavage brittle fracture morphology, the specimen treated by multiphase shows quasi cleavage fracture morphology, and the impact specimen treated by local induction quenching shows ductile fracture morphology, which is resulted from the excellent mechanical properties of the quenched and tempered (Q&T) microstructure. The tested data show that the Q&T plus local induction quenching is more suitable for picks used in hard substrate.

Key words: 42CrMo steel, pick, heat treatment process, microstructure, mechanical properties

CLC Number:

TG156

Yuan Zhizhong, Wang Mengfei, Duan Xubin, Yang Haifeng, Li Biaomin, Luo Rui, Zhao Xiaoqiang, Cheng Xiaonong. Effect of heat treatment on microstructure and mechanical properties of 42CrMo steel picks[J]. Heat Treatment of Metals, 2023, 48(6): 1-8.

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