铝合金激光－MIG 复合焊接头性能研究

摘要

After the interaction of laser-MIG and arc,grain sizes in top welding seam center are different from that in bottom welding seam center.Based on this,the effects of welding speed on the microstructure,tensile property and mi-crohardness of 6009 aluminum alloy are studied.The results show that the tensile strength and elongation of the hybrid joint increase with the increase of welding speed;the fracture position of hybrid welding transfers from welding seam to heat-affected zone(HAZ),and dimple morphologies appear in the fractures,and the mechanism of fracture is micro-porous gathered fracture;grains in the upper welding center are smaller than that in the lower welding center,and its size distribute is uniform.Moreover,the microhardness of top welding seam is greater than that of bottom,and there is welding-softened zone in HAZ,and its width is 4 to 6 mm.%探讨了激光与电弧相互作用后，焊缝中心上部和下部晶粒大小不同的原因，在此基础上研究了焊接速度的改变对6009铝合金接头的微观组织、拉伸性能、显微硬度的影响。结果表明：6009铝合金激光－MIG 焊焊接接头的抗拉强度和延伸率随着焊接速度的增加而增加，拉伸试样的断裂位置由焊缝区转移到热影响区，断口呈现均匀分布的韧窝形貌，断裂机制为微孔聚集形断裂；焊缝中心上部晶粒小于焊缝中心下部，而且尺寸分布均匀。焊缝中心上部的显微硬度则高于焊缝下部。接头热影响区存在软化区，宽度为4～6 mm。