Properties of Braze-Welded Butt Joints of Galvanized Steel Made with a Handheld Welding Laser

Streszczenie:

Braze-welding of galvanized steel using a welding laser aims to reduce damage to the anti-corrosion zinc layer compared with that resulting from the use of the GMAW (Gas Metal Arc Welding) method. Concentrated thermal energy (laser beam) eliminates spatter and reduces the size of the heat-affected zone. This article describes the results of experiments and research on braze-welded butt joints made using a handheld welding laser. The above-named type of joint is unusual for braze-welding of galvanized steel, but results from manufacturing requirements, for example when manufacturing door frames. A CuSi3 filler metal and a 1.5 kW welding laser were used to create the joints. The trials revealed significant problems in filling the gap with filler metal. It was also demonstrated that the wettability of the steel by the CuSi3 filler metal strongly depended on the melting conditions of the filler metal. Furthermore, relatively good joint strength was demonstrated, and the fracture locations were identified during mechanical tests. The properties of the joints depended significantly on the macrostructure and microstructure. It was shown, among other things, that a reduction in weld height and an increase in weld width, while maintaining a similar cross-sectional area, were caused by increasing welding speed (associated with an increase in filler metal wire feed rate), laser power, and beam oscillation range. The laser braze-welding process can cause partial melting of the steel. However, this results in significant changes in the braze-weld structure. 

Słowa kluczowe: braze welding, handheld welding laser, galvanized steel, wettability

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