水素ガス環境下での低合金鋼のき裂進展挙動とAE放出特性の評価

概要

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Slow strain rate tests (SSRT) have been carried out using precracked compact tension specimens of low alloy steels in purified hydrogen gas at ambient temperature. By the use of elastic-plastic fracture mechanics parameters, the influence of hydrogen gas on sub-critical crack growth has been investigated in terms of the J-value at the onset of crack extension and also from a view point of fracture modes. Acoustic-Emission (AE) during the SSRT tests has been monitored to clarify the cracking behavior in hydrogen gas and by mechanical tearing. In a hydrogen gas environment, it is clearly shown that a crack initiates and propagates in a quasi-cleavage manner until applied the J value reaches J_1c and after that the fracture mode changes to mixture of ductile dimple and quasi-cleavage. This result suggests that mechanical tearing occurs at J-values greater than J_1c even in a hydrogen environment. In SA 533 B steels, the AE activity showed two energy peaks with respect to loading levels, whose origins are attributable to the onset of quasi-cleavage fracturing caused by the environment and to the onset of mechanical tearing.
社団法人日本機械学会の論文
1988-01-25