铝合金与钢的搅拌摩擦焊焊缝成形及接头性能

用搅拌摩擦焊方法焊接了异种材料铝合金与低碳钢,分析了接头的截面形貌及力学性能.结果表明,当焊接工艺参数合适时,可以获得表面成形良好、无变形的铝合金与钢的对接接头和搭接接头.对于对接接头,金相分析表明,在焊缝横截面,低碳钢与铝合金呈较好的混合状态,在平行焊缝表面的平面内,两种材料呈交叠分布.力学性能试验表明,焊核内局部区域具有较高的显微硬度,可能是形成了钢与铝的金属间化合物,拉伸试样断裂在焊核区边缘偏低碳钢一侧.对于搭接接头,接合面处的钢呈形似"钳子"或弯钩状的分布,钢铆进了铝合金焊缝中,两种材料能有效地达到塑性结合,接头的抗剪切性能较好.

Weld appearances and mechanical properties of friction stir welded joint of Al alloy and mild steel

Dissimilar materials,aluminum alloy and mild steel,were joined by friction stir welding,and the weld appearance and mechanical properties of joint were analyzed.The results shown that a deformation-free joint with good weld surface appearance can be obtained with suitable welding conditions for butt-joint and lap-joint of the dissimilar materials.For the butt joint,the mild steel and aluminum alloy were mixed well within the weld cross section,and the two kind of materials was intercalated on the middle plane parallel to the weld surface.The microhardness is higher than the mild steel at local place within weld nugget,which perhaps is the formation of intermetallic compound at these points.The joint is fractured from the edge of the nugget at the steel side for the butt-joint.For the lap-joint,the cross section appearance at the weld is somewhat like pincers or hook,that is,the steel is riveting into the aluminum alloy with a curved shape.The two kind of materials could reach plastic joining and the joint have a rather good shear properties.