Effect of welding speed, pulse frequency, and pulse width on the weld shape and temperature distribution in dissimilar laser welding of stainless steel 308 and brass alloy

Laser welding of brass and stainless steel alloys is of special importance due to its wide application in the industries related to energy production. In this study, laser welding of heterogeneous metals was performed in a laboratory. Measurements of the temperature around the molten pool showed changes in the welding conditions. By changing different parameters such as welding speed, frequency, and pulse width, different thermal gradients were obtained. The results showed that the formation of the molten pool was asymmetric, and it was mostly done by melting the brass alloy. Due to the lower melting temperature and the high heat transfer rate of the brass alloy, the measured temperature and the molten volume of this alloy were higher. The microstructure of the molten pool also included intermetallic compounds. Increasing the dimensions of the molten pool (width and depth) by raising the peak power and reducing the welding speed was more effective than other parameters. The microhardness results also indicated the higher weld strength of the brass alloy with stainless steel rather than pure copper. At the range of the investigated process parameters, the adjacent temperature near the molten pool was about 20% (30 °C) higher for the brass alloy, in comparison to stainless steel, when the pulse frequency and pulse width were changed.