Weldability of zinc coated steel sheet by plasma arc welding

The use of zinc coated steel in the automotive industry is rapidly increasing as a result of consumer demand for improved corrosion resistance of automobile bodies. Plasma arc welding of zinc coated steels is currently under investigation, with a strong emphasis on their weldability. In the present study, plasma arc welding has been performed on zinc coated steel with several welding parameters, such as current, travel speed and flow of plasma gas. Those parameters are interrelated in their effect on penetration, in order to produce sound welds. An optimum combination of parameters was sought, which would give full penetration of the weld, with the highest travel speed and no visual defects on every steel-sheet as a basis; hence, characterizing the process in the most interesting way and into a useful industrial applications. It is found that zinc coated steel sheets of 0.7 mm and 1 mm thickness can be welded by plasma arc welding. The microstructures of welds were almost similar. There is a slight difference in chemical composition of the welds because of zinc pick-up which varies from the top surface to the bottom welds. The presence of zinc in the welds did not have any effect on the mechanical properties.