表面处理对A7N01铝合金MIG焊接头疲劳裂纹扩展速率的影响

Abstract

采用CT (紧凑拉伸)试样，对经过不同表面处理的A7N01铝合金MIG焊(熔化极惰性气体保护焊)接头的焊缝区、热影响区和母材区的疲劳裂纹扩展速率(da/dN)进行了试验研究。同时采用维氏硬度计对经表面处理的焊接接头进行了硬度性能检测。结果表明：喷丸、喷砂表面强化处理会提高焊接接头表面的硬度，其中经钢丸强化处理的接头表面硬度值最高。喷丸、喷砂表面强化处理可以在焊接接头表面引入残余压应力，降低“有效拉应力”，从而延长疲劳裂纹的萌生期和降低疲劳裂纹的扩展速率，提高焊接结构的疲劳寿命。 The fatigue crack growth rates (da/dN) of the weld zone, heat affected zone and base metal zone of A7N01 aluminum alloy MIG (Metal Inert-gas) welded joints subjected to different surface treatments were studied by CT specimen. And the hardness of the welded joints was tested by the vickers hardness tester. The results show that: The surface hardness of welded joint is improved by shot peening and sand blasting, and the hardness value of welded joint strengthened by shot peening is the highest. Shot peening and sand blasting can improve the fatigue life of welding structures by introducing residual compressive stress on the surface of welded joints and reducing the effective tensile stress, thus prolonging the initiation period of fatigue crack and reducing the rate of fatigue crack growth.