抄録
A coal-gasification combined-cycle plant requires high efficiency through high-temperature operation. For this purpose, it is necessary to develop such material for gas turbine that has excellent high-temperature strength and hot-corrosion resistance. This circumstance made us pay attention to the single crystal superalloy to be used for blade and vane.
This paper describes the result of experimental investigation on high-temperature strengths of two single crystal Ni-base superalloys, CMSX-2 and CMSX-4, followed by comparison with that of a directionally solidified superalloy, Mar-M247. Through the study, the authors demonstrated that single crystal superalloys were more excellent in high-temperature strength than a directionally solidified superalloy and that the specimens machined from solid blades showed the same high-temperature strengths as those from solid bars.
The authors also carried out high-temperature low-cycle fatigue tests of CMSX-2 with holding. CMSX-2 showed significant decreases in fatigue lives due to holding, especially in compressive holding tests. The results can be explained by using the frequency modified Ostergren's method.
