二相ステンレス鋼の疲労き裂進展挙動に及ぼす微視組織および腐食環境の影響

概要

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Fatigue tests have been conducted on a duplex stainless steel, SUS329J4L, in order to clarify the influence of volume fraction of ferrite and austenite phases on crack growth behaviour in room air and in 3%NaCl solution. Three materials with different volume fractions were prepared with solution treatment at 1050°C, 1150°C and 1250°C, resulting in the volume fractions of austenite phase of 50%, 28% and 12%, respectively. In room air, when the data were characterized in terms of △K, the crack growth rates decreased considerably with increasing solution treatment temperature, T_s. After allowing for crack closure, i. e. evaluated by △ K_<eff> all materials showed almost the same growth behaviour, indicationg that the observed defference in crack growth resistance was attributed to crack closure derived from residual stress and crack path deflections. In 3%NaCl solution, the crack growth rates for all materials were enhanced in high △K or △K_<eff> region. Cleavage fracture in ferrite phase was responsible for the enhanced crack growth, which increased with increasing T_s and △K.
社団法人日本材料学会の論文
1999-12-15