Ni/Si中间层对铝/钢激光焊接头组织与性能的影响

研究了以Ni箔以及预置Si粉的Ni箔为中间层的铝/钢异种金属激光焊行为. 系统考察了不同激光功率下预置Si粉的Ni箔中间层对铝/钢异种金属激光焊接头组织与性能的影响. 结果表明，加入预置Si粉的Ni箔做复合中间层时，与只添加Ni箔片做中间层时相比，焊接接头的最大剪切力明显提高，其中激光功率为2 150 W时焊接接头的最大剪切力提高至1 307.96 N；Si粉的添加增加了熔池的流动性，并使得铝/钢界面的物相组成、元素分布和微观组织形态发生了改变；焊缝区生成了Fe-Si及Al-Si二元新相，有效抑制了Fe-Al二元脆性相的生成，改善了铝/钢的焊接性. 因此，预置Si粉的Ni箔复合中间层的加入，可以有效地改善铝/钢异种金属激光焊过程中的冶金反应，进而提高焊接接头的力学性能.

Effect of Ni/Si interlayer on microstructure and properties of laser welded aluminum/steel joints

The laser welding behavior of aluminum/steel dissimilar metal with Ni foil and Ni foil with Si powder as intermediate layer has been studied. The effect of Ni foil interlayer with Si powder at different power on the microstructure and properties of aluminum/steel dissimilar metals laser welded joints was investigated systematically. The results show that the tensile strength of the welded joint is obviously improved when the Ni foil with Si powder is added as the composite interlayer, the tensile strength of welded joint is increased to 1 307.96 N when the laser power is 2 150 W. The addition of Si powder increases the flowability of the molten pool, and changes the phase composition, element distribution and microstructure morphology of the aluminum/steel interface. Fe-Si and Al-Si binary phases were formed in the weld zone, which effectively suppressed the formation of Fe-Al binary brittle intermetallic compounds and improved the weldability of aluminum/steel. Therefore, the addition of Ni foil composite interlayer with Si powder can effectively improve the metallurgical reaction in the process of dissimilar metals laser welding of aluminum/steel, and then improve the mechanical properties of welded joints.