含硼不锈钢的热变形行为

Hot Deformation Behavior of Stainless Steel Containing Boron

在304不锈钢成分基础上,添加了质量分数1.96%的硼元素,采用真空感应熔炼技术制备含硼不锈钢,对该钢进行单道次热压缩试验,研究了该钢在900~1 150℃和应变速率0.1~10 s-1条件下的热变形行为;根据试验数据,基于Arrhenius方程并结合5次多项式拟合建立该钢的热变形本构模型,对加工硬化率-真应力曲线进行分析确定该钢发生动态再结晶的临界条件。结果表明:在试验参数下热压缩后,含硼不锈钢的流变应力-应变曲线为典型的动态再结晶型,软化机制以动态再结晶为主;随着变形温度的升高或应变速率的减小,试验钢的峰值应力及其对应的真应变降低;采用所建立的热变形本构方程计算得到的真应力-真应变曲线与试验测得的相吻合,平均相对误差绝对值为2.7 6%,说明该本构模型能够准确预测含硼不锈钢的热变形行为;变形温度较高、应变速率较小时,该钢较易发生动态再结晶。

The stainless steel containing boron was prepared by vacuum induction melting technique with adding 1.96 wt% boron into 304 stainless steel.The hot deformation behavior of the steel was investigated by single pass hot compression tests at 900-1 150℃ and strain rate of 0.1-10 s-1.The hot deformation constitutive model of the steel was established by Arrhenius equation with five degree polynomial fitting combined with test data.The critical condition of dynamic recrystallization of the steel was determined by analysis of the work-hardening rate-true stress curves.The results show that the flow stress-strain curves of stainless steel containing boron presented a typical dynamic recrystallization type,and the dominated softening mechanism was dynamic recrystallization after hot compression under the test parameters.With increasing deformation temperature or decreasing strain rate,the peak stress and its corresponding true strain of the test steel decreased.The true stress-true strain curves calculated by the established hot deformation constitutive equation had a good agreement with the test results,and the average absolute relative error was 2.76%,indicating that the constitutive model could precisely predict the hot deformation behavior of stainless steel containing boron.The dynamic recrystallization of the steel occurred easily when the deformation temperature was relatively high and strain rate was relatively small.