High-power fiber laser welding and its application to metallic glass Zr55Al10Ni5Cu30

Fiber laser has been receiving attention due to its advantages of high-power and high-beam quality to produce narrow and deep penetration welds at high-welding speeds. Therefore, fiber laser welding is expected to apply to the joining of metallic glass which has unique properties such as high-mechanical strength or small solidification shrinkage, because extremely rapid quenching for the laser weldment or heat-affected zone (HAZ) is possible to remain amorphous. In this research, fiber laser welding was first performed with the objective of obtaining a fundamental knowledge of weld property produced in bead-on-plate welding for common marital such as Type 304 stainless steel with 6 kW fiber laser beams of several peak power densities. Deeply penetrated weld beads with narrow widths were produced with small spots of tightly focused laser beams and full-penetration welds in 8 mm thick plate could be obtained at the high-welding speed of 4.5 m/min. Subsequently, the tightly focused 2.5 kW fiber laser beam was applied to 72 m/min ultra-high-speed welding for metallic glass Zr55Al10Ni5Cu30 in order to keep amorphous metals. Consequently, the weldment and HAZ remained desirably amorphous at ultra-high-welding speed with a tightly focused fiber laser beam.