Authors:
Minjung Kang
Cheolhee Kim
Welding and Joining Research Group, Korea Institute of Industrial Technology, 7–47, Songdo-Dong, Yeonsu-Gu, Incheon 406–840, Republic of Korea

Jongsup Lee
Molding and Forming Technology R&D Group, Korea Institute of Industrial Technology, 7–47, Songdo-Dong, Yeonsu-Gu, Incheon 406–840, Republic of Korea

There is an increasing demand for ultrahigh-strength steel in automotive industries to facilitate the manufacture of lightweight vehicles without compromising their security features. Although transformation-induced plasticity and dual phase steels have strengths of under 1 GPa, boron-alloyed steel obtained after the hot-press process has a strength of over 1500 MPa. Al–Si-coated steel has been developed to prevent excessive oxidation during high-temperature processes, but the Al–Si coating is known to lower weld properties. In this research, the laser weldability of hot-press-forming steels with and without Al–Si coating was examined. The specimens were laser-welded in butt and overlap joints by using disk and fiber lasers. The influence of the process parameters on the weld strength was investigated.