光纤激光焊接A356铝合金过程气孔敏感性

摘要

In order to decrease the metallurgical porosity and keyhole-induced porosity during deep penetration laser welding of Al and its alloys, and increase the mechanical properties of work-piece, the effects of welding parameters such as laser power, welding speed and defocusing value on both kinds of porosities were systemically analyzed respectively, and the shape and fluctuation of plume of the keyhole were observed to reflect the stability of the keyhole. The results show that increasing laser power or decreasing laser spot size can lead to the rising of both number and occupied area of pores in the weld; meanwhile, the plume fluctuates violently over the keyhole, which is always companied with the intense metallic vapor, liquid metal spatter and collapsing in the keyhole, thus more pores are generated in the weld. The porosity in the weld reaches the minimum at welding velocity of 2.0 m/min when laser power is 5 kW and defocusing value is 0.%为减少激光深熔焊接铝合金过程中产生的冶金型气孔和小孔型气孔，达到提高工件力学性能的目的，系统分析激光功率、焊接速度以及离焦量等工艺参数分别对两种气孔造成的影响，同时观察不同焊接参数下小孔上方的金属蒸汽羽烟形状与波动情况，以反映焊接过程中小孔的稳定性。结果显示，增加激光功率或减小激光光斑半径时，小孔上方金属蒸汽羽烟波动剧烈，形状和大小都极不稳定，间接反映小孔的稳定性更差，因此在焊缝根部产生更多小孔型气孔。当由激光能量密度变化引起的小孔深宽比增高时，小孔内部坍塌的可能性升高，并在焊缝中留下更多的气孔。当激光功率为5 kW、离焦量为0、焊接速度为2.0 m/min时，气孔率达到最小值。