水素ガス環境における高強度鋼の切欠き引張特性に及ぼす水素曝露の影響(<小特集>自動車技術を支える材料力学)

概要

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The effect of hydrogen exposure on high strength steel SCM435 with a sharp notched specimen was investigated. Tensile tests were carried out in hydrogen gas and in helium gas environments. In hydrogen gas environment, the specimen which was not exposed to hydrogen gas and the specimen which was exposed to hydrogen gas for 48h were used. As the result of tensile tests with various notched depth specimens, the tensile strengths of hydrogen gas exposed specimens were higher than that of hydrogen gas non-exposed specimens. The tensile strength increases with hydrogen gas exposed time until hydrogen diffuses homogeneously on tensile tests with the notched t=1.0mm specimens. The fracture surfaces of hydrogen gas specimens showed an intergranular fracture near the notch root where the helium gas specimens showed a fracture mode of microvoid coalescence. The crack initiation stress of the hydrogen gas non-exposed specimen was lower than that of the 48h-exposed specimen.
2009-10-25