Laser Welding of Cobalt-Chrome Alloy and Gold Alloy

Objective: The present study discussed a junctional state with welding cobalt-chromium alloy and type-4 gold alloy together using a laser welder. Method: Cobalt-chromium alloy (hereafter: CO) and type-4 gold alloy (hereafter: AU) were used as material. Each test specimen took the shape of 15x5x1mm, fabricated by casting. The specimens were fabricated followed by fixed to an exclusive jig with butt joint to weld them using a laser welder. After joint, bending strength and the amount of strain were determined through a 3-point bending test. The determination was conducted by 7 with respect to each condition. Following the bending test, the elemental analysis was performed at the welded regions between CO and AU using an x-ray micro-analyzer with observing fracture surfaces using the same machine. Results: The bending strength was 1929MPa for the control CO and was 1065MPa for the welded CO with significant differences found between them (p<0.01). The bending strength was 1613MPa for the control AU and was 621MPa for the welded AU with significant differences found between them (p<0.01). The bending strength was 721MPa for the different-metal welding, CO-AU with significant differences found between CO and AU-CO (p<0.01) as well as between AU and AU-CO (p<0.01). Many voids probably generated during welding were observed in fracture surfaces of the welded specimen. The result of mapping is that the elements at the welded region of CO-AU were distributed ununiformly. Conclusion: As a cause of the bending strength of the welded specimen becoming lower than that of the control, voids and the existence of un-welded regions are considered. It was suggested that joint between different metals, cobalt-chromium alloy and gold alloy with a laser welder was clinically useful.