7A52铝合金焊接结构件疲劳性能研究

用西南铝加工厂生产的6mm厚7A52铝合金板、5A56焊丝,采用手工氩弧焊接的方法,焊接了9件箱形模拟结构件。对其弯曲疲劳性能进行了研究,试验频率为4.5-6Hz,应力比R=0.1。试验后对铝合金模拟结构件疲劳断口形貌进行了微观分析,确定裂纹形成机制。结果表明,7A52焊接模拟结构件的疲劳特性为离散分布,说明模拟结构件疲劳现象是一种较为复杂、相互联系的多因素过程。因此,结合国外资料介绍铝合金焊接结构件的试验数据,经保守估算,7A52焊接结构件的弯曲疲劳寿命N=1×106次的疲劳强度值为σ0.1=45MPa。经扫描电镜微观分析表明,疲劳裂纹源均由焊接缺陷引起。

Research on fatigue behavior of welded 7A52 Al components

The fatigue property of angle-join simulating structure in box-shape was studied. By use of TIG method, 7A52 aluminum alloy sheets in 6 mm thickness manufactured by Southwest Aluminum Machinery Factory were welded with 5A56 as filler wire. Fractograph of simulating structure was analysed and the mechanism of crack was determined. The results show that the fatigue behavior of 7A52 Al welding simulating structure was scattered, which indicates that simulating structure fatigue process is a complicated and interrelated process. Based on experimental data obtained from abroad and conservative calculation, fatigue strength was determined as σ(?)=45 MPa under N=1×106 cycling of bent fatigue life. Microstructure analysis indicates that origin of fatigue crack was introduced by welding defect.