抄録
In order to clarify the relation between creep damage and fatigue damage concerning the rupture life of SUS 316 stainless steel under combined creep-fatigue loading, the behaviors of surface cracks and internal cavities were examined metallographically. The defects were measured quantitatively, and the relation between the defects and the test condition was discussed.
The fracture under combined creep-fatigue loading at 550°C was caused mainly by the formation, growth and linkage of wedge-type intergranular cracks. They were associated with the hardening of matrix due to strain aging under creep loading and fatigue loading. The rupture life under combined creep-fatigue loading at 650°C was determined by the growth of surface cracks under fatigue loading in the combined creep-fatigue loading test. The fracture at 750°C was caused by the inter-granular growth of surface cracks, which were affected by the formation of internal cavities at the surface crack tip.
