bcc金属における疲れき裂伝播の結晶方位依存性

抄録

A study has been made of the crystallographic dependence of fatigue crack propagation in bcc metals using Fe-3%Si alloy coarse grain specimens. A significant crystallographic dependence in fatigue crack propagation is observed. Fatigue cracks do not propagate stably along an unspecific plane normal to the loading axis but incline to change the propagation plane gradually to propagate along a specific plane ({110} or {100}). In this grain, the fatigue striation arrangement direction is changed according to the change of the fatigue crack plane. Analyzing this result, it is revealed that the striations are arranged parallel to the cross-line between a macroscopic crack plane and the {110} or {100} plane.
Various fatigue crack propagation models are discussed in the light of this study, and it is shown that no fatigue crack propagation model can explain adequately this crystallographic dependence. This may be explained by modifying the so-called slip-off process.