光丝位置对铝合金激光填丝焊接过程的影响

为了明晰光丝距离对激光填丝焊接过程影响规律, 采用高速摄像、外观检查、宏观金相等方法, 对3种光束模式下不同光丝距离与激光堆焊关系进行了理论分析和实验验证, 得到了光丝距离对焊丝熔化、熔滴过渡、熔池波动和焊缝凝固的稳定性影响数据。结果表明, 光丝位置由相交(-5mm)向相离(+5mm)变化时, 熔滴过渡经历"液滴→液滴+液桥→液桥→液滴+液桥"阶段; 相同光丝距离时, 单光束激光模式、双光束激光串行模式和双光束并行模式的焊缝熔深依次降低, 甚至出现焊缝偏移和无熔深现象; 单光束模式和双光束串行模式对焊丝熔化和熔池的影响规律近似, 但双光束并行模式下具有特殊性; 单光束激光焊接时, 随着离焦量的增加, 焊缝的熔深由最大值409.8μm迅速减小到282.6μm; 双光束激光串行模式时, 焊缝的最大熔深仅为328.4μm, 随着离焦量降低而减小, 但正离焦量为焊缝截面呈现不对称状态; 双光束激光并行焊接模式时, 焊丝偏向小功率激光束时, 焊缝无熔深; 随着焊丝向大功率激光束移动, 形成仅有226.5μm小熔深焊缝。该研究为铝合金激光增材和焊接提供了参考。

Influence of the distance between laser and wire on the process of aluminum alloy welding with filler wire

In order to clarify the influence of the distance between laser and wire on the process of laser welding with filler wire, theoretical analysis and experimental verification on the relationship between surfacing tests and different distances of laser and wire in three laser mode have been carried out by using high-speed camera, appearance inspection, and macroscopic metallography. The data about the influence of the distance between laser and wire on the stability of welding wire melting, droplet transfer, molten pool fluctuation, and weld solidification during filler wire welding was obtained. The results show that: When the distance changes from -5mm to +5mm, the droplet transition goes through the stages of "droplet→droplet+liquid bridge→liquid bridge→droplet+liquid bridge". With the same distance, the penetration depth of the laser mode from the largest to the smallest is respectively single-beam laser mode, dual-beam laser serial mode, and dual-beam parallel mode, and even the weld offset and no penetration appears at the same time. In addition, the single-beam mode and the dual-beam serial mode have similar effects on the wire and the molten pool, while the dual-beam parallel mode with different energy distributions has the different effect. With the increase of the defocus, the penetration depth of the weld is rapidly reduced from the maximum value of 409.8μm to 282.6μm during the single-beam laser welding. While the maximum penetration depth of the weld is only 328.4μm in the dual-beam laser serial mode, which decreases as the defocusing amount decreases, but the weld cross-section is asymmetrical at positive defocusing amount. In the dual-beam laser parallel welding mode, the weld has no penetration when the welding wire is biased to the low-power laser beam; but a small penetration weld of only 226.5μm is formed as the welding wire moves to the high-power laser beam. This research provides a reference for laser additive manufacturing and welding of aluminum alloy.