熱時効がオーステナイト系ステンレス鋼溶接金属の衝撃特性へ及ぼす影響の評価

抄録

Austenitic stainless steel weld metal are susceptible to thermal aging embrittlement. In this study, the effect of thermal aging on impact behavior of type 316L stainless steel weld metal was evaluated by charpy impact test and microstructural examination. Charpy absorbed energy at RT of both weld metal and cast duplex stainless steel decreased by 50 % after aging at 475°C for 5000 h or 3000 h. In the summarized impact behaviors of various weld metals and cast duplex stainless steels in previous studies, there is no differences in charpy absorbed energy decrease ratio. It depends only on the ferrite content, whether weld metals or cast duplex stainless steels, and the results in this study are also consistent with that. Microstructural examination indicated that the fracture surface varies depending on the anisotropy of ferrite, but it has little or no effect on the charpy absorbed energy decrease ratio.