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为了确定A6N01-T5铝合金挤压型材MIG焊接接头发生疲劳断裂的原因,本文采用高频疲劳试验机对A6N01-T5铝合金MIG焊接试样进行低周疲劳拉伸试验,研究了A6N01-T5铝合金焊接接头低周疲劳行为、疲劳裂纹表面和断口表面以及缺陷对疲劳性能的影响。结果表明:在热影响区存在一个明显的软化区,该软化区在疲劳拉伸实验中变形较严重;A6N01铝合金焊接试样的疲劳裂纹源萌生于气孔及夹杂等缺陷产生应力集中处;焊缝近表面的气孔及内部的夹杂是裂纹快速扩展的诱因。
In order to determine the cause of fatigue fracture of MIG welded joints of A6N01-T5 aluminum extrusion profiles, low-cycle fatigue tests were performed on the A6N01-T5 aluminum alloy MIG welded specimens by high-frequency fatigue testing machine. The effects of A6N01-T5 aluminum Low cycle fatigue behavior of alloy joints, fatigue crack surface and fracture surface, and defects on fatigue properties. The results show that there is a distinct softening zone in the heat-affected zone, which deforms more severely in the fatigue tensile test. The source of fatigue cracks in the welded specimens of A6N01 aluminum alloy originated from stress concentration points such as pores and inclusions. Stitches near the surface and internal inclusions are the causes of rapid crack propagation.