COLLABORATIVE STUDY ON THERMAL FATIGUE PROPERTIES OF HIGH TEMPERATURE ALLOYS IN JAPAN

A collaborative study was conducted by the Subcommittee of the Japanese Society of Materials Science Committee on High Temperature Strength, in order to examine thermal fatigue properties of four Japanese high temperature alloys, and to determine short tensile, creep and isothermal fatigue properties. Thermal fatigue lives of SUS 304 and Hastelloy X were found to be shorter than isothermal fatigue lives at the maximum temperature of the thermal cycle. Intergranular cracks were observed more frequently in in-phase thermal fatigue than in isothermal fatigue at the maximum temperature. The lower bounds of out-of-phase thermal fatigue life and in-phase thermal fatigue life were nearly equal to Manson's pc-type fatigue life and his cp-type fatigue life, respectively. An empirical formula previously reported by the authors was found to be useful as an approximate life prediction of thermal fatigue based on isothermal fatigue lives.