激光液态填充焊的填材熔化与过渡稳定性

针对激光填丝焊过程中焊丝对入射激光能量的反射、匙孔不稳定等问题，提出了激光液态填充焊方法，采用电弧提前预熔焊丝，让填材以液态方式流入熔池中.分析了激光液态填充焊的熔化、过渡模式，以及工艺参数对过渡模式的影响规律.结果表明，在电弧热作用下焊丝有液桥过渡和滴状过渡两种模式，焊接电流较小时，焊丝的上部熔化，下部依然保持固态，形成稳定的液桥过渡；焊接电流较大时，焊丝端部全部熔化易回缩成球为滴状过渡，过渡稳定性变差.为改善滴状过渡的稳定性，可依靠间隙的毛细作用稳定流入熔池中.激光液态填充焊可降低对匙孔的冲击，提高匙孔的稳定性.

Melting of filler metal and transfer stability in laser welding with pre-melting liquid filler

Laser welding with pre-melting liquid filler was developed to suppress the energy reflectivity of laser by filler wire and fluctuation of keyhole during welding process. The liquid filler was pre-melted by arc and then flowed into molten pool. The melting and transfer mode of laser welding with pre-melting liquid filler and the melting and filling characteristics under different process parameters was investigated. The results show that two kinds of transition modes occurred, i.e. liquid bridge transfer and droplet transfer. During laser welding, the upper filler wire was melted and the bottom part remained unchanged at small welding current. On the contrary, droplets formed at the filler wire tip at large welding current, the transfer stability became worse. To improve the stability of droplet transfer, the liquid filler could flow into the molten pool with the help of capillary. The stability of keyhole was improved because the impact of liquid filler on the keyhole was suppressed during laser welding with pre-melting filler wire.