沉淀强化奥氏体合金的氢致断裂行为

研究了未充氢和热充氢沉淀强化奥氏体合金的拉伸断裂行为,分析了其氢脆敏感性与拉伸断裂行为间的联系,研究了氢对合金局部塑性变形及微裂纹形核的影响。结果表明:氢使沉淀强化合金由单一的韧窝断裂转变为韧窝断裂、沿晶断裂和滑移带开裂的混合断裂方式。其原因是:一方面,氢促进位错平面化滑移趋势、加剧局部塑性变形;另一方面,滑移带被晶界、孪晶界以及不同取向的滑移带所阻碍,引起了位错塞积和氢聚集。

Study on Behaviors of Hydrogen-induced Fracture of Precipitation Strengthened Austenitic Alloy

Correlation of hydrogen embritt/ement sensitivity and fracture behavior was investigated by means of tensile tests and fractographic examination in a precipitation strengthened austenitic alloy with and without hydrogen.Additionally,slip bands during tensile deformation were observed in order to determine the effect of hydrogen on localized plasticity and microcrack nucleation.The results show that the fracture mode of the precipitation strengthened austenitic alloy exhibits dramatic transition from dimple fracture in uncharged specimens to the mixed mode with dimple,intergranular and slip band fracture in charged specimens.As for the reason,it can be related to not only the slip planarity and localization induced by hydrogen but also the dislocation pile-up and hydrogen accumulation formed at the sites of grain boundaries,twin boundaries and intersecting slip bands.