铸态42CrMo环坯热辗扩微观组织模拟

Microstructural Evolution of As-cast 42CrMo Ring during Hot Rolling

为避免传统环件热成形工艺需要多次加热等问题,以铸态42CrMo合金环坯短流程铸辗复合成形工艺为研究对象,通过Gleeble-1500D热模拟试验机及金相显微镜进行系列试验研究,得到温度850～1150℃,应变速率0.05～5s-1的流变应力曲线.对流变应力曲线进行图形变换求解出位错密度变化和每个动态再结晶晶粒生长的动力学行为,并评估成核和动态再结晶晶粒的生长动力学行为.研究晶粒拓扑变形技术,并通过主成分分析对晶粒的拓扑结构进行优化.结果表明,采用Kock-M ecking（KM）位错密度模型可以揭示42CrMo合金动态再结晶过程中的位错密度演变,结合元胞自动机和优化后的晶粒拓扑变形技术的KM位错密度模型,能精确地模拟位错密度动态再结晶过程.

In order to avoid traditional ring parts hot rolling process problems of many times heating and so on,the as-cast 42CrMo alloy ring short process flow blank-casting and rolling compound forming process is taken as the research object,a series of experiments are performed on the Gleeble-1500D machine and metallographic microscope,the flow stress curves under temperatures of 850-1150℃ and strain rates of 0.05-5s-1 are obtained.The dislocation density variation and the grain growth kinetics of each dynamically recrystallizing grain are calculated by transforming the flow stress curves.In addition,the nucleation and the growth kinetics of dynamically recrystallized grains are evaluated.The grain topology deformation technology is studied,and the grain topology structures are optimized by use of the principal component analysis.The results show that the Kock-Mecking （KM）dislocation density equation can be employed to calculate the dislocation evolution during dynamic recrystallisation of 42CrMo alloy.The KM dislocation density model coupled with cellular automata method and optimized grain topology transformation technology can simulate dislocation density during dynamic recrystallization process accurately.