二段変動荷重下の疲労変形挙動と転位構造変化

概要

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Fatigue tests with two-step cyclic loading (Low-High and High-Low stress change tests) were carried out on mild steel and stainless steel specimens with different slip characters. Plastic strain range Δε_p changed rapidly with the stress change, and it was investigated from a stand-point of rearrangement of dislocation structures, and compared with the analytical values by dislocation dynamics. The dislocation structures were rearranged easily in the Low-High stress change test. On the other hand, in the High-Low test, the specimen fractured before full rearrangement of dislocation because of surface micro-cracks growth resulting from initial high stress amplitude, but the rearrangement was performed sufficiently by the removal of cracks and by sufficient cycling of second low-stress amplitude. The rate of dislocation rearrangement was expressed clearly by the change of cell structure area and was higher in mild steel because of its ease of cross-slip.
社団法人日本機械学会の論文
1987-08-25