破壊領域観察にもとづく鉄鋼の水素脆化機構に関する研究(第 1 報) : 遅れ割れ現象とその破面形態について

概要

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The hydrogen induced fracture of HT80 steel was investigated by means of three-point bending test and electron fractography. The hydrogn induced crack manifests itself as the lowering of fracture stress and/or lowering of toughness by diffusion and accumulation of hydrogen towards the tip of notch or crack during incubation time. Based on the observation of fracture surface by ESM, the delayed fracture surface at high applied stress level showed dimple pattern and partially quasi-cleavage with more microscopic plastic flow, and with decreasing of applied stress, proportion of dimple pattern decreased, the other way, proportion of quasicleavage fracture increased. In the neighbourhood of lower critical stress, quasi-cleavage fracture with little microscopic plastic flow and intergranular fracture were predominant. The fracture morphology was explained to depend on the kinetics of diffusion and/or accumulation of hydrogen and the fracture surface of delayed cracking was different from cleavage fracture.
社団法人溶接学会の論文
1975-02-05