针对铸造镁合金的激光焊接气孔难题,以AZ91D铸造镁合金为主要材料,紧密围绕气孔产生的原因、影响因素及其控制开展研究。探讨了铸造镁合金激光焊接气孔产生的特点和机理;研究了自熔激光焊接气孔产生的原因及影响因素;研究了填充焊丝激光焊接对焊缝气孔的控制及不同对接间隙焊接的质量控制。研究结果表明:铸造镁合金的激光焊接稳定性和气孔率主要受母材微孔率影响。对于母材微孔率在1-3%的铸造镁合金,采用填充焊丝激光焊接技术,焊缝平均气孔率降低到0.31%;对于母材微孔率在6-10%的铸造镁合金,采用填充焊丝激光焊接技术,使焊缝平均气孔率由20%降低到3%,对接间隙0.4mm时可以进行正常的焊接。

The studies focused to pores of cast magnesium alloy and aimed to the causations of it,the influence and the control factors to it in laser welding process were carried out with the material of AZ91D. The characteristics on the pores caused in laser welding of cast magnesium alloy were discussed. The reasons of the pores caused and the influences on it were searched. Filler wire technique was employed in laser butt joint,with different gaps,of cast magnesium alloy and the control for the pores and welding quality of cast magnesium alloy was achieved. The results showed that the stability and the pore rate of cast magnesium alloy in laser welding were affected mainly by the pore rate in substrate alloy. For the cast magnesium alloy with the rate of 1-3%,when filler wire technique was adopted the pore rate was from 1.5% down to 0.31%. For the cast magnesium alloy with the rate of 6-10%,in same way,the pore rate was from 20% down to 3%. The normal laser welding process could be had in this case.