Fibre laser welding of Zn-coated steel on Al alloy for next generation lightweight vehicles

Abstract

According to new environmental policies announced by European Union, car manufactures have been asked to avoid the unnecessary waste of energy and reduce pollution levels. Replacing steel with lightweight materials on car bodies is considered as one method to reduce the vehicle weight to achieve these requirements. In this study, lap welds of Zn-coated steel on Al alloy, which have recently been used in the automotive industry, were carried out using a single mode fibre laser. The interplay of processing parameters was investigated by means of changing processing parameters such as laser power, welding speed and laser pulse frequency. Metallurgical observations and mechanical tests were undertaken to evaluate the weld quality. Results show that good quality parallel welds with small fusion zones could be obtained even though the processing window to produce defect-free welds is extremely narrow. The amount of heat input and the laser pulse frequency play more important roles than others in pulsed wave fibre laser welding of Zn-coated steel on Al alloy.According to new environmental policies announced by European Union, car manufactures have been asked to avoid the unnecessary waste of energy and reduce pollution levels. Replacing steel with lightweight materials on car bodies is considered as one method to reduce the vehicle weight to achieve these requirements. In this study, lap welds of Zn-coated steel on Al alloy, which have recently been used in the automotive industry, were carried out using a single mode fibre laser. The interplay of processing parameters was investigated by means of changing processing parameters such as laser power, welding speed and laser pulse frequency. Metallurgical observations and mechanical tests were undertaken to evaluate the weld quality. Results show that good quality parallel welds with small fusion zones could be obtained even though the processing window to produce defect-free welds is extremely narrow. The amount of heat input and the laser pulse frequency play more important roles than others in pulsed wave fib...