5083铝合金与304不锈钢异种材料涡流搅拌摩擦搭接焊工艺研究

Vortex-Friction Stir Lap Welding of 5083 Aluminum Alloy/304 Stainless Steel Dissimilar Materials

为解决铝/钢常规搅拌摩擦焊中搅拌头的磨损和断裂问题,对5083铝合金和304不锈钢进行涡流搅拌摩擦搭接焊工艺试验。通过焊缝表面形貌、接头力学性能和横截面界面组织分析,研究倾角、转速和焊速对涡流搅拌摩擦搭接焊接头质量的影响规律。结果表明:在低转速和低焊速条件下,获得了较好的焊缝表面成形;在转速不变的条件下,随着焊速的提高,界面可承受的拉剪载荷逐渐降低;在焊速不变的条件下,随着转速的提高,界面可承受拉剪载荷先略微增大后减小并维持稳定;搅拌工具以2.5°倾角进行涡流搅拌摩擦焊接时,相较于无倾角条件,可以获得更大的焊缝成形工艺参数窗口和更好的冶金结合强度;5083铝合金和304不锈钢界面结合的主要方式为Al原子向不锈钢中扩散,低转速-低焊速组合下形成的扩散层相对更厚。

To avoid tool wear and break in conventional friction stir welding of aluminum/steel,5083 aluminum alloy and 304 stainless steel were lap-welded by vortex-friction stir welding(VFSW).The effect of tool-tilted angle,rotating speed,and welding speed on the VFSW lap joint quality was investigated through the analysis of the weld formation,joint mechanical properties,and cross-sectional interface microstructure.The results show that good weld formation can be obtained at lower rotating speeds and lower welding speeds.Metallurgical bonding occurred between 5083 aluminum alloy and 304 stainless steel.At the rotating speed of 200 r/min,with the increase in welding speed from 15 mm/min to 30 mm/min,the bearable tensile-shear load of the bonding interface decreases from 9.14 kN to 4.59 kN.At the welding speed of 30 mm/min,with the increase in rotation speed from 200 r/min to 400 r/min,the bearable tensile-shear load of the bonding interface increases slightly,then decreases,and finally remains stable.Compared with the tool-tilted angle of 0°,the 2.5°tool-tilted angle can provide a larger process parameter window to obtain defect-free welds and higher metallurgical bonding strengths.The interface microstructure shows that a diffusion layer of aluminum atoms diffusing into stainless steel with a thickness of 1~2μm was formed on the interface.The diffusion layer is relatively thicker at a lower rotating speed and welding speed.