The fatigue behavior of under-aged,peak-aged,over-aged and nature-aged 2A12 alloy in air at room temperature was investigated using a tension-compression fatigue testing machine. The effect of air on the fatigue fractures was studied by means of scanning electron microscopy (SEM). The results showed that the cycle number of fatigue breakdown increased obviously with the cyclic stress decreasing for each aged 2A12 alloy, the lower the cyclic stress level , the more obvious increased the fatigue lifetime, in atmospheric environment with a room temperature. The fractures of every-aged state in air at room temperature are transgranulars, in which fatigue striations,steps and dimples are observed, and more areas with fatigue striations exist under lower cyclic stresses. Tyre-like patterns are observed on fatigue fractures in air for the under-aged and peak-aged. The best fatigue crack growth resistance is revealed at the natural aging state, then it is decreasing in order of the under-aged ,peak-aged state and the over-aged state. The reason for the effect of air on the fatigue behavior of every-aged 2A12 alloy was discussed.
|||VINOGADOV A;HASHIMOTO S;MIURA S .Fatigue crack lnitiation and propagation in oriented copper single crystals in vacuum and in air[J].Scripta Materialia,1996,34:775-779.|
|||KICHIRO ENDO;KENJIRO KOMAI .Fatigue crack propagalion in an aluminum alloy in ultra-high vacuum[J].Journal of the Society of Materials Science Japan,1977,26:143-148.|
|||KHIREDDINE D;KHIREDDINE M H .Low cycle fatigue behavior of an aluminium alloy with small shearable precipitates[J].Effect of Surface Coating,2000,22:585-591.|
|||VERKIN B I;GRINBERG N M .The effect of vacuum on the fatigue behavior of metals and alloys[J].Materials Science and Engineering,1979,41:149-181.|
|||WANG R;MUGHRABI H .Fatigue of copper single crystals in vacuum and in air[J].Materials Science and Engineering,1984,65:219-243.|
|||SLIVIK D C;BLANKENSHIP C P;STARKE JR E A et al.Intrinsic fatigue crack growth rates for Al-Li-Cu-Mg alloys in vacuum[J].Metallurgical and Materials Transactions,1993,22(03):1807-1817.|