高強度鋼の動 SCC き裂進展の下限界特性

概要

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Sustained load tests were conducted on a high-strength steel SNCM 439 sensitive to hydrogen embrittlement with or without vibratory stresses of small amplitude, superimposed. Furthermore, varying load tests (stress ratio R being near zero) were carried out to compare with those mentioned above. The relation among static SCC under sustained load (R = 1.0), cyclic SCC under varying load (R being near zero) and dynamic SCC under high-cycle vibratory stresses superimposed (R being near unity) were discussed, in contrast with those in 7N01 A1 alloy sensitive to active path corrosion type SCC. Similarly as those in 7N0I alloy, the threshold stress intensity factor K_<max>=K_<DSCC> considerably decreased from K_<ISCC> at R=1.0. However, K_<DSCC> at a stress ratio of 0.95 hardly decreased from K_<ISCC>. On the other hand, in the Region II, where a subcritical crack growth appears, the crack growth rate in 7N01 alloy increased with a decrease of R. However, in SNCM 439 steel the smaller the stress ratio was, the slower the crack growth rate was. In SNCM 439 steel static SCC was dominant in the Region II just the same as cyclic SCC for the material sensitive to hydrogen embrittlement.
社団法人日本材料学会の論文
1982-08-15