基于40Cr高温动态力学性能的磨削表面动态再结晶行为

通过分离式霍普金森压杆(SHPB)实验得到了40Cr合金钢在高温高应变率下真应力-真应变曲线，据此确定了材料发生动态再结晶的临界条件.采用解析法和实验法分别求解了磨削强化层的温度场和塑性应变场分布.结果表明，磨削强化层在磨削深度方向具有较大的温度和塑性应变梯度;150μm强化层内会发生奥氏体转变;磨削表面最高温度可达1060℃.在磨削亚表面60μm内会产生剧烈的塑性变形，达到了再结晶的临界条件.较大的磨削深度使磨削强化层塑性应变增大，再结晶现象越充分，微观组织细化程度越高.

Dynamic Recrystallization Behavior of Grinding Surface Based on 40Cr High Temperature Dynamic Mechanical Properties

Through the split Hopkinson pressure bar experiment， the true stress-true strain curves of 40Cr alloy steel at high temperature and high strain rate are obtained. Then， the critical conditions for dynamic recrystallization of 40Cr are determined. An analytical method and experimental method are used to solve the temperature field and plastic strain field distribution of the grinding strengthening layer(GSL). The results show that the GSL has a large temperature and plastic strain gradient in the direction of grinding depth. The austenite transformation occurs within 150μm of the GSL. The maximum temperature of the ground surface can reach 1060℃. The severe plastic deformation can occur within 60μm of the ground subsurface， which reaches the critical condition of the dynamic recrystallization(DRX). With the larger grinding depth， the plastic strain of GSL increases， the DRX behavior is more sufficient， and the degree of microstructure refinement is higher.