超高強度TBF鋼の遅れ破壊特性に及ぼすγ_R特性の影響

概要

論文の詳細を見る
To develop the ultra high-strength steels having excellent delayed fracture resistance, effects of retained austenite characteristics on hydrogen absorption properties and delayed fracture properties of ultra high strength low alloy TRIP-aided steels with bainitic ferrite matrix (TBF steels) were investigated. The hydrogen concentration of TBF steels were increased with increasing volume fraction of retained austenite. It was considered that the hydrogen which charged to the TBF steels was mainly trapped in retained austenite and/or on retained austenite/matrix interface. The TBF steel with high carbon concentration of retained austenite indicated high delayed fracture strength. This was expected that (1) hydrogen-assisted and/or stress-assisted martensite transformation of retained austenite was suppressed by existence of the stabilized or carbon enriched retained austenite, (2) hydrogen was trapped in refined interlath retained austenite films and (3) localized stress concentration was relaxed by strain induced plasticity of retained austenite.