Al-Si共晶合金の回転曲げおよび引張圧縮超長寿命疲労特性

概要

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To investigate the effect of the Si-phase on fatigue properties of Al-Si eutectic alloys in a long life fatigue range (N≦10^7) and super long life fatigue range (N>10^8), rotating-bending and tension-compression fatigue tests and FEM analysis were carried out. Fatigue test specimens were prepared from two materials produced by two processes: continuous casting and extrusion. The results obtained are as follows. In the case of continuous casting, all fatigue fractures were caused by shear-type cracks, resulting in shorter fatigue life. In the case of extrusion, the fatigue fracture origin in the long life fatigue range was in the Si-phase, while in the super long fatigue range it was in the matrix. The fatigue limit defined by the cycle N=10^7 can be predicted using the √<area> parameter model, i.e. with two parameters, the maximum size of Si-phase √<area>_<max> and the Vickers hardness H_v of Al-marix, without the influence of the Si-phase. In the case of Al-Si alloy, a crack leading to fracture initiates even after 10^8 cycles under very low stress. Thus, super long life fatigue behavior must be taken into account to both material and structural designs.
社団法人日本機械学会の論文
1996-02-25