热变形对轴承钢G80T晶粒细化行为的影响

利用Gleeble-3800热模拟变形试验机,对高温轴承钢G80T的动态再结晶行为及相关力学性能进行了研究。通过对该钢在1 050℃下以10s-1的变形速率进行0%~70%的不同形变量的单道次压缩,研究了不同形变量下热变形钢的微观组织结构及硬度。结果表明:当形变量在20%时,无动态再结晶发生;当形变量达到40%时,热变形组织出现了部分的再结晶晶粒;随着形变量的进一步加大,再结晶晶粒数目增多,形变量达到60%后,形变组织形成了平均晶粒尺寸为2.8μm的完全再结晶组织。同时由于形变和晶粒尺寸大幅度细化,钢中的碳化物也随着形变量的增加而逐步减少。通过对压缩应力-应变曲线软化行为的分析,认为该钢的再结晶属于动态再结晶;在1 050℃进行60%的形变可以实现该钢的完全动态再结晶,将平均晶粒尺寸从原始的22μm细化到2.8μm,同时将钢的硬度从820 HV提高到895 HV。研究结果表明,动态再结晶是细化高温轴承钢G80T晶粒尺寸和提高性能的一种有效措施。

Effect of hot compression deformation on grain refinement behavior of bearing steel G80T

The dynamic recrystallization behavior and the corresponding mechanical properties of high temperature bearing steel G80T were studied by Gleeble-3800 thermal deformation simulation machine. The microstructure and the microhardness of the studied steel after single pass compression of 0%-70% under 1050?? with the deformation rate of 10s-1 were examined and studied. It is found that no recrystallized grain can be found in the specimen after hot compression of 20%, some recrystallized grains can be found in the specimen after hot compression of 40%, and fully recrystallized microstructure with average grain diameter of about 2. 8??m is found in the specimen after hot compression of 60%. Further more, the quantity and sizes of carbides in the steel decrease with increase of hot compression strain. Based on the analysis of the stress-strain curve of the hot compression, it is concluded that the recrystallization behavior of the steel is dynamic recrystallization during hot compression process. The fully dynamic recrystallization occurs after compression of 60% at 1050??, which results in the grain refinement from 22 to 2. 8??m and increase of microhardness from 820 to 895HV. The results show that dynamic recrystallization is an effective method to refine the grain size and enhance the mechanical properties of high temperature bearing steel G80T.