Abstract:The high cycle fatigue fractography of 5A06 aluminum alloy was investigated by means of optical mi鄄
croscopy(OM), scanning electron microscopy( SEM) and energy dispersive spectrometer( EDS). The results show
that the fatigue cracks mainly initiate at the interface between impurities and matrix when the loading stress is near the
fatigue limit. Multi鄄source fatigue cracks appear with the increase of the stress and the cracks originate mainly from
the broken impurities. The crack deflection path becomes more complex, the fatigue striation increases and the fatigue
expansion area becomes smaller with the stress increasing. The direction between adjacent grain favored slip planes
determines the deflection of the micro鄄crack in the early stage of the fatigue crack propagation.
