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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。
The effect of strain rate on the reduction of alloy cross-section during the high-temperature tensile test was studied, and the mechanism was also analyzed. The alloy was stretched to fracture at 500 ℃ with different strain rates (1.43 × 10-6 ~ 1.33s-1), and the reduction of area was tested. The grain boundary composition was observed by electron probe. The results show that the strain rate increases from 1.43 × 10-6 s-1 to 1.43 × 10-2 s-1, and the reduction of area decreases, reaching the lowest value at 1.43 × 10-2 s-1. Then, as the strain rate increases to 1.33 s-1, the cross-sectional shrinkage increases. Electron probe test confirmed that the sample with the lowest reduction in area had sulfur segregated on the grain boundaries and no grain boundary segregation of sulfur was observed in the samples stretched at other strain rates. Based on the microscopic theory of elastic deformation of polycrystalline metal, the results of these experiments are analyzed, and it is confirmed that this alloy has the basic characteristic of strain rate brittleness in the tensile test - the critical strain rate.