J. Zhou, Pennsylvania State University, USA
H.L. Tsai, Missouri University of Science and Technology, USA
This chapter first describes the history and current status of the laser welding technology. Then, fundamentals of laser welding, such as keyhole formation and collapse, laser-plasma interaction, weld pool dynamics, porosity formation mechanisms, metal melting and solidification, etc., are elaborated. Finally, new developments in laser welding such as hybrid laser-arc welding, multi-beam laser welding, electromagnetically assisted laser welding, and future challenges and development of laser welding are discussed.