Product Code: ICAL08_1005

Distribution of Wire Feeding Elements in Laser-arc Hybrid Welding
Authors:
Lin Zhao, National Institute for Materials Science; Tsukuba, Ibaraki Japan
Susumu Tsukamoto, National Institute for Materials Science; Tsukuba, Ibaraki Japan
Tomohiro Sugino, National Institute for Materials Science (Present Address:Ihi); Yokohama Japan
Goro Arakane, National Institute for Materials Science; Tsukuba, Ibaraki Japan
Presented at ICALEO 2008

One of the advantages of the laser-arc hybrid welding is to attain the improved microstructure and mechanical property of the weld metal by feeding filler materials. In this case, the alloying elements should be distributed homogeneously in the weld metal. In the present paper, the effect of welding variables on the distribution of the alloying elements has been investigated. Some driving forces acting on the molten pool have also been discussed to understand the distribution behaviour of the alloying elements. Full penetration hybrid welding was carried out on 11 mm thick 0.1C-1.3Mn-0.3Si steel. Molten metal flow on the pool surface and inside the sample was observed by a high-speed video camera and a micro-focused x-ray transmission imaging system, respectively. For homogeneous distribution, it is effective to promote the molten metal flow towards inside of the keyhole (inward flow). Leading laser is more effective to attain the homogeneous distribution, since the arc plasma jet promotes the inward flow. Addition of more than 2 % oxygen in the arc shielding gas is also effective for the homogeneous distribution, since the inward Marangoni flow is promoted.