316FR鋼のクリープ疲労相互作用に及ぼす大気環境効果

抄録

Creep-fatlgue tests were conducted using 316FR stainless steel at 650°C in air under a variety of strain time programs including symmetric continuous, unsymmetric continuous and strain hold cycles. By comparison of the results with test data obtained in vacuum, it was found that the life reduction which occurred for a slow tension-fast compression strain wave and the tensile strain holding wave was smaller in air than in vacuum, and that the symmetric continuous cycle gave the largest life reduction from the data obtained in vacuum. Following the creep-fatigue tests, fracture surfaces were investigated by SEM. When time/rate-dependent life reduction occurred, the fracture mode in vacuum was intergranular, but in air, striations were observed and integranular fracture was rarely observed.