Laser welding copper with hight power CW blue laser

Abstract

This paper will report the bead on plate test results with a 275 Watt Continuous Wave blue laser, for welding Copper foils up to 500 µm thick, and the bead on plate test results for a 500 Watt Continuous Wave blue laser up to a 1 mm thickness. The high absorption (∼65%) at this wavelength enables both the conduction mode and keyhole mode welding regimes resulting in highly stable weld puddles. Metallurgical analysis of the weld beads will be presented and clearly shows the transition between conduction mode welding and keyhole mode welding of the Copper as well as minimal porosity and no gaps in the weld bead due to melt ejection. The conduction mode welding process results in a micro-structure that is nearly identical to the base material. The weld bead exhibits a uniform Vickers hardness similar to the base material through the heat affected zone. The keyhole mode is observed with a characteristic “hourglass” shape but the micro-structure is significantly different than the base material as observed in deep penetration welds. Welding of multiple layers of thin Copper was demonstrated for both the conduction mode and keyhole mode welding processes. The stability of the weld puddle during the process results in minimal ejection of molten material producing virtually no spatter on the surface of the part being welded. The high coupling efficiency of this wavelength makes the blue laser the ideal source for stably welding these highly reflective materials.This paper will report the bead on plate test results with a 275 Watt Continuous Wave blue laser, for welding Copper foils up to 500 µm thick, and the bead on plate test results for a 500 Watt Continuous Wave blue laser up to a 1 mm thickness. The high absorption (∼65%) at this wavelength enables both the conduction mode and keyhole mode welding regimes resulting in highly stable weld puddles. Metallurgical analysis of the weld beads will be presented and clearly shows the transition between conduction mode welding and keyhole mode welding of the Copper as well as minimal porosity and no gaps in the weld bead due to melt ejection. The conduction mode welding process results in a micro-structure that is nearly identical to the base material. The weld bead exhibits a uniform Vickers hardness similar to the base material through the heat affected zone. The keyhole mode is observed with a characteristic “hourglass” shape but the micro-structure is significantly different than the base material as observed in ...