Laser-Arc Hybrid Welding Of High-Strength Steels

Laser-arc hybrid welding is a new developing welding technology, which has been well developed abroad, however it is still under the stage of fundamental research in our country. In this paper, the aim of the paper is to study laser-arc hybrid of high-strength steels .In this paper, a CO2 laser combinated with MIGwas used to weld high-strengh steels, the microstructure and mechanical characters were studied systematically by SEM, TEM and XRD etc. The experimental results indicate that martensitic phase transformation takes place in the weld bead during crystallization; its microstructure consist of martensitic and lots of retained austenite;heat affected zone's microstructure are martensitic and retained austenite,its crystal grain grow larger obviously; harding zone precipitate carbide,its microstructure are martensitic and a few retained austenite; Higher laser power makes the weld bead and heat affected zone's crystal grain refine, the content of martensitic increase, the hardness becomes higher; higher the speed of welding makes the weld bead and heat affected zone's crystal grain refine, the content of martensitic increase, the modification of welding current and gap have little influence to the microstructure of the weld bead and heat affected zone. Laserhybrid is able to implement nicer bridging; the tensile strength of the welding joint is higher than the parent metal; the hardness of weld bead is lower than laser, and has a good uniform.