铝合金激光焊接气孔缺陷形成及抑制机理

Formation and inhibition mechanism of porosity defects in laser welding of aluminum alloy

气孔是铝合金激光焊缝重要的缺陷形式,对焊缝力学性能具有较大的影响。综述了铝合金激光焊接中气孔缺陷的形成及抑制机理。氢气孔和由不稳定匙孔塌陷造成的气穴是铝合金气孔缺陷的两种主要类型。氢气孔的形成与熔池中氢的溶解度剧变密切相关,通过减少氢的进入量以及获得合适的熔池冷却速度可有效抑制氢气孔数量。匙孔的稳定性是影响气穴形成的主要因素,通过采取合适的工艺措施改善熔池流动行为、增大匙孔尺寸,可明显提高匙孔稳定性,减少气穴数量。

Porosity is an important weld defect in laser welding of aluminum alloys, which can influence the mechanical property of welds significantly. In this papex,the mechanisms of porosity formation and inhibition in laser welding of aluminum alloys are reviewed in detail. Hydrogen pores and porosity caused by the collapse of unstable keyhole （named by gas cavity） axe the two main porosity types in aluminum alloys. Hydrogen pore is closely related to the drastic change of hydrogen solubility during the solidification process of molten pool. The content of hydrogen pore can be reduced by reducing hydrogen content and obtaining proper cooling rate in molten pool. Keyhole stability is the main factor affecting the formation of gas cavity. To improve the fluid flow and enlarge keyhole size by proper processing can improve the keyhole stability obviously, which can reduce the quantity of gas cavity in laser welding of aluminum alloys.