Cr17铁素体不锈钢的应变速率脆性

研究了Cr17铁素体不锈钢在高温拉伸试验过程中应变速率对合金断面收缩率的影响,并对其发生机制进行了分析。合金在500℃下以不同应变速率(1.43×10-6~1.33s-1)拉伸至断裂,测试断面收缩率,并利用电子探针对晶界成分进行了观察测试。结果表明:应变速率从1.43×10-6 s-1升高至1.43×10-2 s-1,断面收缩率降低,约在1.43×10-2 s-1时达到最低值。然后,随着应变速率增加至1.33s-1,断面收缩率升高。经电子探针测试证实,断面收缩率达到最低值的样品,硫在晶界上偏聚,其他应变速率拉伸的样品没有观察到硫的晶界偏聚。基于多晶金属弹性变形的微观理论,分析这些试验结果,证实了此合金在拉伸试验中具有应变速率脆性的基本特征——临界应变速率。

Strain rate embrittlement for Cr17 ferritic stainless steel

The effect of strain rate on reduction of area (RA) for Cr17 ferritic stainless steel during tension test under high temperature was studied and the mechanism was analyzed. The tension tests were tested at 500?? and different strain rates from 1. 43??10-6 to 1. 33s-1 and the concentrations of elements at grain boundary were tested by electron probe microscopic analyzer (EPMA). The results show that RA decreases with strain rate increasing from 1. 43??10-6 to 1. 43??10-2s-1 and is the minimum at strain rate of 1. 43??10-2s-1. Then RA increases with strain rate increasing to 1. 33s-1. According to EPMA results, when RA is the minimum, S segregates at grain boundary. However, segregation of S at grain boundary is not observed with other strain rates. Based on the elastic deformation theory of polycrystalline metals, these experimental results verify that the critical strain rate which is the basic characteristic of strain rate embrittlement exists during tension test of this steel.