Fe-3.2wt.%Si合金単結晶の疲労き裂先端における繰返しすべり挙動におよぼす水素ガスの影響

概要

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Fatigue crack propagation tests using a single-crystalline Fe-3.2wt.%Si alloy are conducted for the purpose of investigating the effect of hydrogen gas on cyclic slip around the crack tip. The crack propagation rate is found to be larger in hydrogen gas than in non-hydrogen (helium) gas. The fracture surface and the near-tip cross-section of {110} crack are observed in detail by using a scanning electron microscope (SEM) and a transmission electron microscope (TEM), respectively. The observation reveals that, in helium atmosphere, the propagation is attributed solely to a ductile plastic rocess. In hydroen atmosphere, the propagation can be also attributed to a ductile plastic process except that the amount of plastic deformation is small and the cyclic slip is concentrated around the crack tip region. Different types of slip systems are found to be operative in helium and in hydrogen gas atmospheres, which is postulated to be correlated to the slip concentration and the increased propagation rate.
社団法人日本機械学会の論文
2009-08-25