6N01-T5铝合金焊接接头疲劳断裂分析

为了确定6N01-T5铝合金挤压型材焊接接头发生疲劳断裂的原因,对6N01-T5铝合金型材及其焊接接头分别进行了疲劳试验,获得了它们的S-N曲线及条件疲劳极限.分析了接头的显微组织与力学性能,并对疲劳断口进行分析,得到了6N01-T5铝合金焊接接头的疲劳断口特征.结果表明,接头显微组织为-αAl与-αAl和Mg₂Si的伪共晶,主要缺欠为气孔;在热影响区与母材交界处存在一软化区,该软化区会引起静载断裂,但不是构件发生疲劳断裂的主要原因;位于焊缝表面焊接缺欠以及构件的表面状态是影响接头疲劳性能的主要原因.

Fatigue failure analysis of 6N01-T5 aluminum alloy welded joints

To identify the main cause of fatigue failures of welded joints of 6N01-T5 aluminum alloy extrusions, fatigue tests were carried out upon 6N01-T5 aluminum alloy extrusions and their weld joints, and S-N curves and conditional fatigue limits of them were obtained.Microstructure and mechanical properties of the welded joints were investigated.The fatigue fractures of the joints were analyzed and thereby the characteristics of them were obtained.The results show that the microscopic structure of the joints is α-Al and pseudo eutectic made up of α-Al and Mg₂Si;the defects of the joints are mainly gas cavities;there is a soften zone between HAZ and base metal which lead to fracture under dead-load but hardly to fracture failure;the main influence factors of fatigue performance are defects on the surface of weld and the surface condition of the weldment.