Creep Behavior of 15-15Ti Austenitic Stainless Steel

The creep test of domestic 15-15Ti 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 15-15Ti 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 exponent of 15-15Ti stainless steel were 14.3, 8.2, 4.9 at 600, 650, 700 ℃, respectively. The creep deformation mechanism was dislocation creep. The short-time creep rupture characteristic of 15-15Ti 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.