抄録
Influence of thermal ageing on the low-cycle fatigue life of SUS 321 stainless steel was investigated in the temperature range from room temperature up to 800°C. A large influence was observed when the fracture mode was intergranular. The aged specimens had always longer fatigue lives than the solution-treated specimens. This difference in fatigue life was caused by the difference in intergranular crack propagation rate. On the other hand, when the fracture mode was transgranular, the influence of ageing on the fatigue life was scarecely observed in the total strain range vs. fatigue life relationship. In the plastic strain range vs. fatigue life relationship, however, a little influence was observed, which was caused by the difference in the cyclic hardening behaviors between the aged and the solution-treated specimens.
