Tong Ying, Zhang Yu-Qing, Zhao Jiang, Quan Guo-Zheng, Xiong Wei
School of Intelligent Manufacturing and Automobile, Chongqing College of Electronic Engineering, Chongqing 401331, China.
Chongqing Key Laboratory of Advanced Mold Intelligent Manufacturing, School of Material Science and Engineering, Chongqing University, Chongqing 400044, China.
Materials (Basel). 2021 Dec 11;14(24):7636. doi: 10.3390/ma14247636.
Refined microstructures achieved by cyclic heat treatment significantly contribute to improving the wear resistance of steels. To acquire the refined microstructures of 65Mn low-alloy steel, first, the specimens were solid solution-treated; then, they were subjected to cyclic heat treatment at cyclic quenching temperatures of 790-870 °C and quenching times of 1-4 with a fixed holding time of 5 min. The mechanical properties of 65Mn low-alloy steel in terms of hardness, tensile strength, elongation and wear resistance were characterized. Afterwards, the effect of cyclic heat treatment on microstructure evolution and the relationships between grain refinement and mechanical properties' improvement were discussed. The results show that the average grain size firstly decreased and then increased with the increase in the quenching temperature. Hardness increased with grain refinement when the temperature was lower than 830 °C. Once the temperature exceeded 830 °C, hardness increased with the temperature increase owing to the enrichment of carbon content in the martensite. With the increase in cyclic quenching times, hardness continuously increased with grain refinement strengthening. In addition, both tensile strength and elongation could be significantly improved through grain refinement. The relationships among wear loss, hardness and average grain size showed that wear resistance was affected by the synthesis reaction of grain refinement and hardness. Higher hardness and refined grain size contributed to improving the wear resistance of 65Mn low-alloy steel.
通过循环热处理获得的细化微观组织对提高钢的耐磨性有显著贡献。为了获得65Mn低合金钢的细化微观组织，首先对试样进行固溶处理；然后，在790-870℃的循环淬火温度和1-4次的淬火次数下进行循环热处理，保温时间固定为5分钟。对65Mn低合金钢在硬度、抗拉强度、伸长率和耐磨性方面的力学性能进行了表征。随后，讨论了循环热处理对微观组织演变的影响以及晶粒细化与力学性能改善之间的关系。结果表明，平均晶粒尺寸随淬火温度的升高先减小后增大。当温度低于830℃时，硬度随晶粒细化而增加。一旦温度超过830℃，由于马氏体中碳含量的富集，硬度随温度升高而增加。随着循环淬火次数的增加，硬度随着晶粒细化强化而不断增加。此外，通过晶粒细化，抗拉强度和伸长率都能得到显著提高。磨损损失、硬度和平均晶粒尺寸之间的关系表明，耐磨性受晶粒细化和硬度的综合反应影响。较高的硬度和细化的晶粒尺寸有助于提高65Mn低合金钢的耐磨性。
