Influence of wire feeding speed on laser brazing zinc-coated steel with Cu-based filler metal

Laser overlap brazing of zinc-coated steel using CuSi 3 filler metal was performed. Many factors affect the quality of the joint in the laser brazing process, such as laser power, brazing speed, and defocusing distance. This study concerns the investigation of the influences of wire feeding speed on the overlap joints during the process of laser brazing. The characteristics of laser brazing on zinc-coated steel are systematically analyzed in terms of the weld molding, microstructure, tensile test, and micro-hardness test. The results show that a large number of dispersed phases were found in the overlap joint which was identified as (Fe 5 Si 3 (Cu)). These (Fe 5 Si 3 (Cu)) phases have a great influence on joint’s mechanical property as proved by the tensile test and micro-hardness test. The joint fails in a way of mixing fracture mode. The crack initiation at the toe of the joint and the crack that propagated to the middle of the joint are ductile fractures. The crack that propagated to the top of the joint adjacent to the base metal and finally failed is a brittle fracture.