50Mn18Cr4V无磁钢的热变形行为

Hot Deformation Behavior of 50Mn18Cr4V Non-magnetic Steel

通过高温压缩热模拟实验，研究了50Mnl8Cr4V高锰无磁钢在变形温度为900～1100℃、应变速率为0．1～10s-1条件下的热变形行为．结果表明，VC第二相的应变诱导析出对50Mn18Cr4V的热变形行为产生重要影响．当变形温度为900～1000℃，应变速率为5s-1时，VC第二相不能充分析出，与应变速率为1s-1相比，对动态再结晶的阻碍作用减弱．应尽量使实验钢在高温段完成热加工，并适当提高应变速率．随着变形温度降低到950oC以下，材料的塑性变差，若以较低的应变速率变形，容易造成晶界开裂；应变速率过高，容易造成流变失稳，因此，以5s-1的应变速率变形，较为适宜．确定了50Mnl8Cr4V无磁钢的再结晶激活能为776．9kJ／mol．通过实验数据回归，建立了实验钢的高温变形抗力模型．

The hot deformation behavior of 50Mnl8Cr4V non-magnetic high manganese steel within the strain rates of 0. 1 -10 s-1 and deformation temperatures of 900 -1 100 ℃ was studied by high temperature uniaxial compression tests. The results show that strain-induced precipitation of VC particles has an important effect on the hot deformation behavior of the tested steel. When the deformation temperature is 900 - 1 000 ℃ and the strain rate is 5 s-1, the precipitation of VC is insufficient and then the suppression of dynamic recrystaUization is weakened, compared with that at the strain rate of 1 s-1. It is better for the total reduction to be accomplished in relatively higher temperature regions with an appropriate strain rate. As the deformation temperature decreases below 950 ℃, the hot plasticity is poor so that the thermal cracking prefers to occur at lower strain rates and the tendency of flow instability increases at higher strain rates. Accordingly, the optimized strain rate is 5 s-1 during hot working process. Furthermore, the activation energy of the tested steel is 776. 9 kJ/mol for hot deformation. The mathematic model of deformation resistance at high temperature was also established.