Abstract
Thermal fatigue tests were conducted for austenitic stainless steel, SUS310S for boiler. The higher the heating temperature the smaller the number of heat cycles for thermal fatigue crack initiation is. The higher the heating temperature the faster the crack propagation rate is. The thermal fatigue crack propagation rate of SUS310S steel was slower than that of SB410 steel. Striation was predominantly observed on fracture surfaces of SUS310S steel. The striation spacing per cycle, S obtained from the measured striation spacing ⊿S versus ⊿K curve was well coincident with the da/dN〜⊿K curve in relatively higher ⊿K region at all heated temperature. It can be concluded that thermal fatigue crack of boiler steel SUS310S propagate in association with striation.
