基于位错密度理论的核级316LN不锈钢高温本构模型

Constitutive Model Based on Dislocation Density Theory for Nuclear-Grade 316LN Stainless Steel at Elevated Temperatures

研究了316LN奥氏体不锈钢在1050~1200℃、应变速率0.1,1和50 s^(−1)下的压缩变形行为,分析了变形温度和应变速率对热流曲线的影响。基于位错密度理论,建立了316LN钢的热变形本构模型,并揭示了316LN钢的软化机理。结果表明,在高温低应变速率(小于0.1 s^(−1))条件下,动态再结晶(DRX)为主导软化机理;在高温高应变速率(大于1 s^(−1))条件下,动态回复(DRV)为主导软化机理;在高温及应变速率为0.1和1 s^(−1)条件下,DRV和DRX共同作用。构建的模型可以很好地预测316LN钢的热变形行为,其Pearson相关系数为0.9956,平均相对误差绝对值为3.07%,为一个精确的本构模型。

The compression deformation behavior of 316LN austenitic stainless steel was investigated at 1050~1200℃ under strain rate of 0.1,1,50 s^(−1).The influence of deformation temperature and strain rate on the hot flow curves was analyzed.Based on the dislocation density theory,the hot deformation constitutive model of 316LN steel was established.The softening mechanism of the 316LN steel was revealed.The results show that the dynamic recrystallization(DRX)dominates the softening mechanism under the condition of high temperature and low strain rate(<0.1 s^(−1));the dynamic recovery(DRV)dominates the softening mechanism under the condition of high temperature and high strain rate(>1 s^(−1));DRX and DRV dominate the softening mechanism under the condition of high temperature and strain rate of 0.1,1 s^(−1).The established constitutive model can precisely predict the hot deformation behavior of 316LN steel:its Pearson correlation coefficient is 0.9956 and the average absolute value of relative error is 3.07%,indicating the accuracy of this constitutive model.