激光封焊高硅铝合金焊缝组织缺陷及应力分析

Microstructure defects and stress analysis of laser sealed high silicon aluminum alloywelds

使用光学显微镜、扫描电镜、X射线应力分析仪等测试分析手段,对激光封焊盒体(壳体Al-50%Si,盖板Al-27%Si,质量分数)的焊缝组织缺陷及焊后残余应力分布进行试验分析研究。发现激光封焊盒体焊缝中存在气孔、热裂纹等缺陷。气孔的类型可以分为两种,第一类气孔由于尺寸较小,并不会对盒体质量产生较大影响,而尺寸较大的第二类气孔虽出现较少,但是对盒体影响较大;此外,焊接热裂纹分布很少且尺寸较小,对盒体影响较小。X射线应力分析结果显示,封焊盒体焊缝中均存在压应力,且残余应力值在(-10)^(-70)MPa之间,最大值出现在盒体四边中点处,并且残余应力最大值约为原材料屈服强度的1/2左右。

The defects and residual stress distribution in the weld area of the laser sealed Al-Si box were characterized by OM,SEM and X-ray stress analyser.Some defects,such as pores and hot cracks,were displayed in the weld seam.Depended on the pore size,the pores could be divided into two types.The first kind of pores with small size can impose an little effect on the quality of the laser welding box,while the second kind of pores with big size can impose great effect on the quality of the laser welding box.Moreover,a small number of hot cracks with small size were manifested in the weld seam,leading to exerting little effect on quality of the laser welding box.X-ray stress analysis results show that the distribution of residual stress in the welded joints ranges from-10 to-70 MPa.The maximum value of residual stress located at the midpoint of the four sides of the laser welding box is about half of the yield strength of the base material.