高速激光电弧复合焊接高强钢焊缝的形貌及成形机理

Appearances and Formation Mechanism of Welds in High-Strength Steels by High Speed Laser-Arc Hybrid Welding

以3mm厚高强钢为试验材料,采用光纤激光-熔化极稀有气体保护焊电弧复合焊接方法,研究了焊速为5m·min-1时激光功率与电弧电压对焊缝形貌的影响,并与低速焊接中厚板得到的焊缝形貌进行了比较。研究结果表明,增大电弧电压和激光功率均能提高焊接过程的稳定性,获得良好的焊缝成形。在不同的热源位置下,焊缝形貌会出现浅"Y"型和深"Y"型的区别。通过高速摄影发现,当激光前置时,熔滴尺寸较大,且过渡时易发生汽化爆炸,对熔池的冲击较大;当电弧前置时,匙孔稳定存在,液态金属能沿着孔壁向下流淌,增大熔池底部面积。在低速焊接中厚板时,由于焊接线能量及工件的表面张力存在差异,焊缝形貌与高速焊接薄板时得到的形貌不一致。

The 3 mm thick high-strength steels are taken as test materials and the technique of fiber laser-arc hybrid welding assisted by metal inert gas is chosen. The effects of laser power and arc voltage at welding speed of 5 m·min-1 on weld appearances are investigated. The comparison with those weld appearances generated in low speed welding of thick plates is conducted. The research results show that the increases of laser power and arc voltage can ensure the improvement of welding stability and the obtainment of good weld formation. There exist different shallow and deep Y-type weld appearances at different heat source positions. The high-speed photography indicates that the droplet size is relatively large in the laser leading mode. In addition, it is prone to vaporization and explosion in the transfer process. Thus, the impact on molten pool are relatively strong. In contrast, in the arc leading mode, the keyholes are stable. The liquid metal flows down along the keyhole walls and thus the bottom area of molten pool increases. As for the low speed welding of thick plates, the weld appearances are not consistent with those for high speed welding of thin plates due to the differences in welding line energy and surface tension of workpieces.