Effect of normalizing pretreatment on microstructure and mechanical properties of 28MnB5 steel for high-speed plough

doi:10.13251/j.issn.0254-6051.2023.01.024

Abstract

Abstract: Aiming at solving the problem of insufficient strength and toughness of domestic soil-engaging components,the influence mechanism of normalizing-quenching-tempering (N-Q-T) process on microstructure and mechanical properties of 28MnB5 steel was studied, and compared with the high-speed ploughing parts produced by quenching-tempering (Q-T) process.The results indicate that the microstructure of N-Q-T and Q-T 28MnB5 steel is mainly comprised of lath martensite. However, the average width of lath martensite of N-Q-T 28MnB5 steel(0.9 μm) is significantly lower than that of Q-T 28MnB5 steel(1.5 μm), and the strength and toughness of N-Q-T 28MnB5 steel are significantly higher than that of Q-T 28MnB5 steel. A further analysis based on the Hall-Petch relationship reveals that the strength improvement of N-Q-T 28MnB5 steel is related to the refinement of lath martensite. At the same time, due to the refinement of lath martensite,the high angle grain boundaries ratio of N-Q-T 28MnB5 steel (34.9%) is higher than that of Q-T 28MnB5 steel (25.1%), which is beneficial for generating more retained austenite to inhibit the crack propagation and indirectly improve toughness.

Key words: 28MnB5 steel, normalizing pretreatment process, grain refinement, strength and toughness

CLC Number:

Huang Hao, Ni Haohao, Ju Yulin, Yuan Zhizhong, Guo Shun, Chang Ya'nan, Wang Dongfa. Effect of normalizing pretreatment on microstructure and mechanical properties of 28MnB5 steel for high-speed plough[J]. Heat Treatment of Metals, 2023, 48(1): 139-144.

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