Effect of Material Degradation and Austenite Grain Coarsening on the Creep life Prediction in 3.5 Ni-Cr-Mo-V Steel

3.5Ni-Cr-Mo-V 강의 크리프 수명예측에 재질열화 및 오스테나이트 결정립 조대화가 미치는 영향

Several methods have been developed to predict on the remaining life of the old power plants. However, Larson-Miller parameter, one of existing creep life prediction methods, has not reflected the effect of material degradatioin and grain size. So this study has been carried out to research the effects of material degradation and austenite grain coarsening on the life prediction of 3.5Ni-Cr-Mo-V steel. An experimental result shows that carbide coarsening has no significant effects on the creep rupture life and the Larson-Miller parameter, but grain coarsening has an important influence on the creep ruptrure life and the Larson-Miller parameter. Therefore Larson-Miller constant, K should be determined to consider on the chemical composition and the grain size of materials.