Experimental and statistical analysis of pulsed Nd:YAG laser welding process for dimension optimization of connection in the AISI 316L stainless steel thin-walled tube

Due to the importance of the weld quality in pressurized equipment, this research investigates the application of Nd:YAG pulse laser in welding of thin-walled AISI316L steel pipes. The input parameters include current intensity, pulse width, frequency, rotational speed, and compressive force applied to the seam of the two tubes being welded. Depth of weld penetration and the weld depth-to-width ratio (aspect ratio) were selected as two output characteristics. The relationship between input and output parameters was obtained by fitting regration functions on the data of central composite design (CCD) of experiments. According to the analysis of variance, the influence of the ratio of compressive force applied to the weld seam to the aspect ratio is 2.5%, and total influence of pulse width and the current on each of the two outputs is 84%. Completion of the depth of penetration and increasing of the weld aspect ratio are two main findings of the optimization process. In the end, to improve the joint quality, based on the optimal level of the parameters, samples were laser-welded in a chamber filled with argon. With this regard, aspect ratio, tensile strength, and failure strain at the samples manufactured by optimum parameters in argon chamber, were improved by 14%, 7%, and 37% compared to samples in normal condition (protection of the molten pool with an argon nozzle), respectively.