Si含量对Al-Mn-Mg合金激光焊接性能的影响

研究Al-Mn-Mg铝合金板材的Si含量（0．1％～0．5％，质量分数）对其脉冲激光焊接性能的影响。试验材料为实验室制备的0．45mm厚的H16态板材。激光焊接试验后发现，当Si含量低于0．34％时，焊池里没有产生裂纹；但是，当Si含量增加到0．47％时，焊池里有裂纹产生。微观组织观察表明，当Si含量低的时候，晶界上残留的共晶相呈不连续的点状分布：当Si含量高的时候，晶界上残留的共晶相变成连续分布。这种现象可以解释增加Si含量对激光焊接性能产生的不利影响。

Effect of Si content on laser welding performance of Al-Mn-Mg alloy

The correlation between Si content （0.1%-0.5%, mass fraction） and pulse laser welding performance of AI-Mn-Mg aluminum alloy sheets was studied. The sheets were fabricated in the laboratory, with gauge of 0.45 mm, H16 temper by pulse laser welding. It was found that no cracking existed in the welding pool as Si content was below 0.34%. However, when the Si content increased to 0.47%, cracking formed in the welding pool. Microstructure observations indicated that residual eutectic phases distributed at the grain boundaries were discontinuous and appeared to be small particles in lower Si content alloys; the residual eutectic phases distributed at the grain boundaries were partially continuous and appeared to be films in higher Si content alloys. These phenomena could explain why Si content adversely affected the laser welding performance.