長期使用後のSUS321ボイラー管材のクリープき裂伝ぱ挙動

概要

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In order to investigate the behavior of creep crack propagation in a boiler superheater tube (Type 321 stainless steel) after long service, the unused and 120 000 hours used materials produced at the same lot were made into test specimens and creep tests on the smooth specimens and creep crack propagation tests on the center notched plate specimens were carried out. The results obtained were summarized as follows: (1) The crack propagation rate, dl/dt, of the used material was faster than that of the unused material at higher Stress levels. However, this difference in dl/dt decreased as the applied stress decreased. These results arose from the difference in creep deformation property of two materials. (2) Roughly, the crack propagation rate, dl/dt, was correlated well with the creep J integral (i. e., C^* parameter or modified J integral), A, and the correlation was identical for both materials. (3) Strictly speaking, the crack propagation rate, dl/dt, was accelerated at lower stress levels, because of decrease in creep fracture strain, ε_f. Therefore, better correlation was achieved between dl/dt and the fracture strain modified creep J integral, J^^._c/ε_f.
社団法人日本材料学会の論文
1984-02-15