SUS304鋼およびNi-Mo-V鋼の高温低サイクル疲労き裂伝ぱ特性と破壊形態

概要

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In order to investigate the behavior of elevated temperature low cycle fatigue crack propagation in Type 304 stainless and 2.5Ni-0.5Mo-0.1V ferritic steels, load-controlled low-cycle fatigue tests were carried out on notched specimens under four kinds of loading waveform (i, e., PP-, PC-, CP- and CC-types). The results obtained were summarized as follows: (1) Type 304 stainless steel The crack propagation rate, dl/dN, was correlated well with the fatigue J-integral range, ΔJ_f, in P-type (i, e., PP- and PC- types) fatigue tested at 973 K and 823 K The striations, of which width was found to be nearly equal to dl/dN, were observed on their fracture surfaces. On the other hand, dl/dN in C-type (i.e., CC- and CP-types) fatigue tested at 973 K was correlated well with the creep J-integral range, ΔJ_c. The fracture node in this case was of intergranular type. However, good correlation of dl/dN with ΔJ_c as well as ΔJ_f wasn't obtained in C-type fatigue at 823 K, where the fracture node was of mixed (i, e., intergranular and transgranular) type. This appeared to be caused by creep-fatigue interaction. (2) Ni-Mo-V steel In the same way of the above stainless steel, dl/dN in P- and C-type fatigue at 823 K were correlated well with ΔJ_f and ΔJ_c, respectively. However, there was no difference in fracture mode between these two types, both of which exhibited the transgranular fracture mode.
社団法人日本材料学会の論文
1984-03-15