AL6XN超级奥氏体钢高温拉伸时的动态应变时效

Dynamic strain aging effect during high-temperature tensile test of AL6XN super austenite steel

研究了固溶处理AL6XN超级奥氏体钢在温度773～973K以及3.3×10-5～3.3×10-3s-1应变速率范围的高温拉伸力学行为。结果表明,AL6XN奥氏体钢在以上实验条件下(不包括873K,3.3×10-5s-1)均存在动态应变时效,具体表现为在真应力-真应变曲线上出现锯齿形,同时屈服强度在773～973K范围呈现平台区;临界应变量随着温度从773K升高到923K逐渐降低,并且在此温度范围激活能为304kJ/mol,说明动态应变时效的机制为AL6XN奥氏体钢中Cr和Mo等置换原子与位错的交互作用。透射电镜分析同时表明AL6XN奥氏体钢形变后位错结构呈平面滑移特征。

The tensile behavior of solution-treated AL6XN austenitic steels was investigated at 773-973 K and strain rates from 3.3×10-5 to 3.3×10-3 s-1.The results show that the serrated flow and plateaus in flow stress is observed for AL6XN steel during the hightemperature tensile-tests at above conditions（excluding 873 K,3.3×10-5 s-1）,suggesting the occurance of dynamic strain aging.The critical strain of the serrated flow decreases with temperature increasing from 773 to 923 K,and the activation energy for the interaction between substitutional solutes,such as chromium,and molybdenum and dislocations is 304 kJ/mol,which is considered as the mechanism of dynamic strain aging.TEM observations reveal a planar slip mode for dislocations in the deformed AL6XN austenitic steel.