6061-T6铝合金激光．电弧复合高速焊气孔形成及控制机制

Formation and Controlling Mechanism of Pores in Laser-TIG Hybrid Welding of 6061-T6 Aluminum Alloys at High Peed

采用激光-钨极氩弧焊(TIG)复合热源对6061-T6铝合金进行了高速焊接,研究了焊接电弧电流、激光脉宽及脉冲频率等工艺参数对气孔形成的影响规律。结果表明,在6061-T6铝合金高速激光-TIG复合焊中,焊接速度的提高使得熔池冷却速度加快,焊缝组织出现细小的等轴晶,热影响区的软化区宽度减小。熔池冷却状态的变化造成"匙孔"稳定性降低并容易坍塌,焊缝中极易形成气孔。随着激光脉宽的增大,焊缝中的气孔数量减少,尺寸减小;随着激光脉冲频率的增大,焊缝中的气孔数量先减少后增加;当电弧电流从180A增大到200A时,焊缝中的气孔数量明显减少。

The 6061-T6 aluminium alloys are welded by the laser-TIG hybrid heat source at a high speed. The influences of process parameters such as arc current, laser pulse duration and laser frequency on pore formation are studied. The results show that, in the process of laser-TIG hybrid welding of 6061-T6 aluminum alloys at a high speed, the increase of welding speed makes the cooling speed of molten pool increase, there exist thin isometric crystals in the weld microstructure, and the width of softening zone in the heat affected zone decreases. The change of the cooling state of the molten pool results in the reduction of keyhole stability, the easy collapse of keyholes, and the easy formation of pores in welds. With the increase of laser pulse duration, the number of pores decreases, and the diameter also decreases. With the increase of laser pulse frequency, the number of pores first decreases and then increases. When the arc current increases from 180 A to 200 A, the number of pores in welds significantly reduces.