抄録
It is necessary to reduce maintenance cost and extend the life of gas turbine blade which is one of the important parts of gas turbine. Various life extension methods (Heat treatment, HIP(Hot Isostatic Pressing)) which recover creep and fatigue damage of gas turbine blade due to long term service are proposed. But there is no quantitative report about the effect of these methods on life extension of gas turbine blade. In this report, we described mechanical properties and microstructure of second stage blades for 1100℃ class gas turbine, which refurbished by heat treatment and HIP after service. Following are the conclusion of this investigation, microstructure degradation (coarsening of γ' phase), creep damage, thermal fatigue damage and ductility loss due to service exposure can be recovered by the previous refurbishment as same as virgin material. Difference between effect of HIP and that of heat treatment are almost negligible. It is possible to extend the life of second stage blades for double by using the previous refurbishment.
