Experimental investigation of the effects of laser parameters on the strength and size of the weld nugget in laser spot welding of stainless steel sheet 316

With the advancement of technology and the great need for thin and light parts with high strength, the need for welding thin sheets has also increased. Nowadays, laser spot welding is used to connect thin sheets of austenitic stainless steel in the production of kitchen wares. The strength and size of the weld nugget are two important parameters in determining the quality of laser spot welding. In this study, thin sheets of stainless steel 316 with a thickness of 0.7 mm were laser spot welded. To perform this welding, a medium power Nd: YAG laser welding machine was used and the effects of effective laser parameters on the strength and size of the weld button were investigated experimentally. Laser frequency at three levels of 5, 7 and 9 Hz, peak laser power at three levels of 1670, 1750 and 1800 W and pulse ON time at three levels of 6, 8 and 10 milliseconds were selected as parameters and test levels. Taguchi L9 method was used to design the experiments. The experimental results show that with increasing laser power, the diameter of the welding button decreases, with increasing the pulse ON time, the diameter of the welding button first increases and then decreases, and with increasing laser frequency, the diameter of the welding button decreases and then increases. In addition, with increasing pulse ON time and laser frequency, the strength of weld nugget increases, and with increasing laser power, the strength of weld button increases firstly and then decreases.