Laser Weldability and Formability of Hot Rolled Steels for Hydroforming Applications

Lee, Won-Beom; Lee, Jong-Bong

Journal of KWJS 2004;22(6):19-24.
Published online January 26, 2005.

[기술논문] 하이드로포밍용 열연 강재의 레이저 용접성 및 성형 특성

Laser Weldability and Formability of Hot Rolled Steels for Hydroforming Applications

Abstract

The laser welding and its analysis of thin-sheet carbon steels were carried out with high power CO₂ laser. The main factor of weld quality of laser welding is gap and edge quality. This work was preformed to focus on the gap tolerance problem during laser welding. First, bead on plate welding of thin sheet was examined to investigate the effect of laser welding variables) and to obtain optimum welding condition. Butt welding was also carried out to show the effect of gap on the laser weldability of thin sheet. In order to investigate the effect of gap on formability of welded thin sheet, LDH test was carried out. At high welding speed, the partial penetration was obtained by low heat input. Otherwise, porosity was formed in the bead at low weld speed because of too much heat input. The optimum welding condition of welding was derived from bead width, penetration and hardness property. The maximum gap tolerance on laser welding was observed to be about 0.2mm. This gap size has good relationship with beam size of laser spot(about 0.3mm). The formability of welded sheet was about 80% value of base metal and the gap size has not affected on the formability, although weld quality is dependent on the gap size.