腐食環境下の高強度鋼疲労き裂進展挙動に及ぼす負荷履歴の影響

概要

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The effects of loading history and corrosive environment on the retardation in crack growth were investigated in rotating bending. The material used was 200℃ tempered SNCM439. Tests were made at two-step varying loading, K_1→K_2, in room air and in 1%NaCl solution. The stress intensity was estimated by K=σ_<max>√<πa/2> for convenience sake, where σ_<max> is the stress amplitude and a is the crack length measured circumferentially on the surface. The results obtained are as follows: (1) The number of retardation cycles was influenced by the environment, K_2, and the intermediate treatment (ex. hydrogen charge) during the change in K from K_1 to K_2. (2) The retardation crack length was determined by K_1, irrespective of environment. (3) The relationship between the number of retardation cycles and a parameter of varying load, (K_1-K_2)/K_2, was derived for each environment. The number of retardation cycles increased linearly with (K_1-K_2)/K_2. (4) The crack propagation rate in retardation period decreased with an increase in K_1 and increased with an increase in K_2.
社団法人日本材料学会の論文
1984-07-15