冷作模具钢深冷处理组织和应力演变的RVE模型分析

RVE Model Analysis on Microstructure and Stress Evolution of Cold Work Die Steel during Deep Cryogenic Treatment

对Cr8Mo2SiV冷作模具钢的微观组织进行定量表征,重构其淬火后的代表体积元(RVE)模型,并对其深冷处理过程进行微观尺度的数值分析,讨论深冷处理过程中微观组织和应力的演变规律。结果表明:深冷处理过程中应力的产生和演变由相变应力主导,显微组织界面上的等效应力要明显大于奥氏体或马氏体内的等效应力,最大等效应力发生在奥氏体和马氏体的界面处,约769 MPa;在深冷处理过程中,碳化物界面附近产生了明显的应力集中,促进了残留奥氏体向马氏体的相变;深冷处理前后应力大幅度变化为细小均匀碳化物的沉淀析出提供了所需的驱动力。

Microstructure of cold work die steel Cr8Mo2SiV was quantitatively characterized and its representative volume element(RVE)model after quenching was also reconstructed.The micro-scale numerical analysis of RVE model during deep cryogenic treatment(DCT)was performed to discuss the evolution law of microstructure and stress in RVE.The investigation suggested that the generation and evolution of stress in RVE during DCT was dominated by the phase transformation stress.The effective stress at the microstructure interface was significantly greater than that in austenite or martensite.The maximum effective stress occurred at the interface of austenite and martensite,about 769 MPa.During DCT,the obvious stress concentration occurred around the carbide interface,which promoted the phase transformation from retained austenite to martensite.The dramatic changes in the stress before and after DCT provided the necessary driving force for the precipitation of fine and uniform carbides.