S0305-5-5 マグネシウム合金AZ80押出し材の疲労強度特性に及ぼす応力比の影響([S0305-5]超長寿命)

概要

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In order to investigate the effect of stress ratio on high-cycle fatigue properties of an extruded magnesium alloy, axial loading fatigue tests have been performed under three testing conditions of stress ratio, R, of 0, -1 and -1.5 at room temperature in ambient atmosphere using hourglass shaped specimens of AZ80 magnesium alloy extruded (F) and T5-againg treated after extruded (T5). A fatigue limit appeared in the F-specimen only under the testing condition of R=0, while that appeared in the T5-specimen under all stress ratios, because of retardation in crack growth by aging microstructure. From detailed observation of fracture surface, crack initiation mechanism changed from the twin deformation induced in high-stress amplitude level to slip deformation induced in low-stress amplitude level, because of a texture caused by extrusion and the particular deformation characteristics of hep lattice structure in a magnesium alloy.
2010-09-04