摘要:采用钨极惰性气体保护(Tungsten inert gas, TIG)焊辅助激光熔钎焊方法,实现了 5A06 铝合金/镀锌钢异种金属涂粉的 对接熔钎焊连接,观察分析对接接头焊缝成形、界面微观结构,并测试接头的力学性能。结果表明:选择合适的焊接参数, 采用电弧辅助激光熔钎焊方法能够得到良好的铝/镀锌钢对接接头,辅助电弧使得铝合金母材的熔化量显著增多,提高了液 态金属在钢背面的润湿铺展,促进了铝/镀锌钢对接接头底部的界面反应。钎焊界面上反应形成不均匀分布金属间化合物层, 厚度为 3~12 μm,其厚度随着焊接电流的增加而增大。通过能谱(Energy dispersive spectrometer, EDS)和 X 射线衍射(X-ray diffraction, XRD)分析表明,一种为向镀锌钢基体内生长的呈锯齿状的 Fe 2 Al 5 ,另一种为向焊缝侧生长的呈絮状的 Fe 4 Al 13 。 随着焊接电流的增大,熔钎焊接头的抗拉强度先增大后减小,接头的抗拉强度最高可达 163 MPa。接头的底部和焊缝/镀锌

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... 采用此方法可增加液态金属对母材的润 湿铺展能力,获得力学性能良好的熔钎焊对接接头。 关键词:铝/钢;电弧辅助;熔钎焊;金属间化合物;力学性能 中图分类号:TG457 Abstract:The butt welding-brazing joining of 5A06 aluminum alloy to the galvanized steel sheet with filler powder is successfully conducted by a new welding method named the arc-assisted laser welding-brazing. The weld bead appearance and the interfacial microstructure of butt joint are analyzed, and the tensile strength of the joint is measured. The results indicate that a high quality welding-brazing joining can be achieved using the appropriate welding parameters. With this new technology, the assisted arc greatly makes the melting of aluminum increased, and effectively enhances the wetability of liquid metal on the back of steel. In addition, the interfacial reaction is improved at the bottom of the joint. A non-uniform intermetallic compounds(IMC) is formed by the galvanized steel reacting with the melted metal at the interfacial layer, and this reaction layer thickness is not constant along the seam-steel joint since it varies from 3 to 12 μm. The thickness of IMC increases with the increasing of welding current. Energy dispersive spectrometer(EDS) and X-ray diffraction(XRD) show that the one is Fe 2 Al 5 , tongue-like, close to steel substrate. The other is Fe 4 Al 13 , floccule-like, close to the seam. When the welding current increases from 10 A to 20 A, the tensile strength of the brazed-fusion welded joint firstly increases and then decreases. Its maximum tensile strength is up to 163 MPa. The fracture begins at the bottom of the joint and the lower part of the welded seam-steel interfacial layer, which is the weak bonding zone of the joint. Comparing with the single laser welding-brazing method, the reactive wetting and spreading behavior of molten aluminum on steel are improved with the assisted arc, thus the superior joint strength can be obtained in the condition. Key words:aluminum alloy and steel;arc-assisted;welding-brazing;intermetallic compounds;mechanical property