15-15Ti奥氏体不锈钢的蠕变性能

Creep Behavior of 15-15Ti Austenitic Stainless Steel

在600,650,700℃下对国产15-15Ti不锈钢进行不同应力水平的蠕变试验,观察了蠕变断口形貌,研究了该钢的蠕变变形机理与断裂机理。结果表明:在不同温度和应力下,15-15Ti不锈钢的蠕变曲线可以分为减速蠕变、稳态蠕变和加速蠕变三个阶段,稳态蠕变阶段的时间占整个蠕变的90%以上;随着应力的降低,稳态蠕变阶段越来越明显,蠕变寿命延长,蠕变伸长率减小;15-15Ti不锈钢在600,650,700℃下的应力指数分别为14.3,8.2,4.9,蠕变变形机理为位错蠕变;15-15Ti不锈钢的短时蠕变断裂性质为穿晶断裂,长时蠕变断裂性质为沿晶断裂,穿晶断裂呈现韧性断裂特征,沿晶断裂呈现明显的晶界空洞损伤机制。

The creep test of domestic 15-15 Ti stainless steel was carried out at 600,650,700℃under different stress levels,and the creep fracture morphology was observed.The creep deformation mechanism and fracture mechanism of the steel were investigated.The results show that the creep curve of 15-15 Ti stainless steel was divided into three stages,including decelerating creep stage,steady creep stage and accelerating creep stage,and the time of steady creep stage accounted for more than 90%of the whole creep time.With the decrease of stress,the steady creep stage became more obvious,the creep life increased,and the creep elongation decreased.The stress exponentof15-15 Tistainlesssteelwere14.3,8.2,4.9 at600,650,700℃,respectively.The creep deformation mechanism was dislocation creep.The short-time creep rupture characteristic of 15-15 Ti stainless steel was transgranular fracture,and the long-time creep rupture characteristic was intergranular fracture.The transgranular fracture showed ductile fracture features and the intergranular fracture showed an obvious grain boundary cavitation damage mechanism.