Heat-resistant steels used in thermal power plant require periodic inspections for safely operation. In order to determine the period of inspection interval, it is necessary to predict not only creep crack growth life, but also creep crack initiation life, which is the time when crack length takes some specified value. Furthermore, it is also necessary to evaluate not only the life of base metals but also that of weld joints which are contained in actual structures. In this research, the life of creep crack initiation for both of base metals and weld joints are evaluated.
