7A52铝合金MIG焊接力学性能及腐蚀行为研究

发布时间：2018-11-09 11:46

【摘要】：研究目的:铝合金凭借其较高的强重比和较为稳定的性能,成为装备轻量化首选结构材料,在应急维修领域,在经济性、效率和灵活性等方面,电弧焊一直处于不可替代的位置,电弧焊中又以MIG焊接维修方法应用较为广泛。轻量化焊接装备常受到酸雨环境的侵扰,特别是组织成分不均匀的焊接接头区域,铝合金焊接接头的腐蚀行为机理目前还尚有争议。方法:本论文针对4mm厚度7A52铝合金板,通过拉伸性能测试优化铝合金MIG焊接的焊后工艺参数,以10ml/L HCl+30g/L NaCl实验环境条件代替酸雨环境条件,进行焊接接头腐蚀行为倾向测试,模拟并验证焊接接头应力场的正确性,通过应力分布揭示腐蚀机理。主要结论如下:(1)7A52铝合金焊接结构件拉伸性能最佳焊接工艺参数为:焊接电流180A,焊接速度40cm/min。平均抗拉强度可达到312.4MPa,焊接接头系数为66.5%。(2)耐蚀性最佳的接头极化电位表征测试参数为:焊缝为-0.612V,热影响区为-0.540V,基体为-0.528V。(3)形貌分析表明,焊缝耐蚀性优于基体,电化学表征测试焊缝腐蚀倾向大于基体,二者矛盾原因是由于焊接接头残余应力场的作用,焊缝中心形成拉应力区,基体为压应力区,铝合金焊接接头腐蚀倾向大小与接头存在的应力场有关。拉应力越大,腐蚀倾向越大,压应力越大,腐蚀倾向越小。
[Abstract]:The purpose of the research is that aluminum alloy has become the first choice structural material for light weight equipment by virtue of its high strength weight ratio and relatively stable performance. In the field of emergency maintenance, aluminum alloy has been used in economy, efficiency, flexibility, and so on. Arc welding has always been in an irreplaceable position, and MIG welding maintenance method is widely used in arc welding. Lightweight welding equipment is often disturbed by acid rain environment, especially in the area where the microstructure is not uniform. The corrosion behavior mechanism of aluminum alloy welded joint is still controversial. Methods: according to 4mm thickness 7A52 aluminum alloy plate, the parameters of post-welding process of MIG welding of aluminum alloy were optimized by tensile property test, and the acid rain environment was replaced by 10ml/L HCl 30g/L NaCl experimental environment. The corrosion behavior of welded joints was tested, the correctness of stress field was simulated and verified, and the corrosion mechanism was revealed by stress distribution. The main conclusions are as follows: (1) the best welding process parameters of 7A52 aluminum alloy welding structure are: welding current 180A, welding speed 40cm / min. The average tensile strength can reach 312.4MPa, and the welding joint coefficient is 66.5. (2) the best corrosion resistance of the joint is -0.612V for weld and -0.540V for heat-affected zone. (3) the corrosion resistance of the weld is better than that of the matrix, and the corrosion tendency of the weld is higher than that of the matrix. The reason of the contradiction between them is the effect of the residual stress field of the welded joint, and the corrosion tendency of the weld is higher than that of the matrix. The tensile stress zone is formed in the center of the weld and the matrix is the compressive stress zone. The corrosion tendency of the aluminum alloy welded joint is related to the stress field of the joint. The greater the tensile stress, the greater the corrosion tendency, the greater the compressive stress and the smaller the corrosion tendency.
【学位授予单位】：长春工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TG457.14

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