板状切欠材のクリープ主き裂発生寿命への粒内および粒界強度の影響

概要

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Effect of grain and grain boundary strengths on the life of main creep crack initiation in a notched plate specimen was investigated, using an austenitic heat resisting steel. In a range of lower grain strength below about H_V 300, the life of main crack initiation increases with an increase in grain strength, independent of grain boundary strength. In a range above H_V 300, however, it decreases drastically with increasing grain strength when a specimen has a weaker grain boundary strength. On the contrary, if a specimen has a stronger grain boundary strength, it continues to increase with increasing grain strength. Further, a relationship between the main crack initiation life, t_i, and the mean notch opening displacement rate, V^^・_m, that is, t_iV^^・^n_m=C (n and C are constant), was obtained which was analogous to the Monkman-Grant relationship. Finally, the effect of grain and grain boundary strengths on t_i was discussed in terms of the relationship t_iV^^・^n_m=C, considering the effect of both strengths on V^^_m and a critical notch opening displacement at the time of main crack initiation.
社団法人日本機械学会の論文
1989-10-25