Al-Zn-Mg-Cu系合金の疲労き裂伝ぱ特性に及ぼす結晶粒寸法の影響

概要

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A fatigue crack growth test on Al-Zn-Mg-Cu alloys with various grain sizes was carried out using CCT specimens (T-direction) to investigate the relationship between fatigue crack growth resistance and the grain size of the alloy. The main results are as follows : (1) The effect of grain size was observed relationship between fatigue crack growth rate, d (2a) / dN, and stress intensity factor range, ΔK. The fatigue crack growth resistance in these alloys depended on the average grain size, ds. (2) The fatigue fracture pattern changed at d_s=24.1μm. In d_s⪈24.1μm, the intergranular fracture decreased with increasing d_s. On the other hand, the intergranular fracture in d_s>24.1μm increasing d_s, and the de-touched cracks and branching along the grain boundary were observed with increasing d_s. Therefore, the transition behavior of the fatigue crack route was closely related to the fatigue crack growth resistance in this alloy. (3) The relationship between grain size and plastic zone size corresponding to the applied stress level at the crack tip is one of the most important factors in fatigue crack growth resistance of Al-Zn-Mg-Cu system alloys.
社団法人日本機械学会の論文
1997-11-25