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Modelling and Optimization of Nd:YAG Laser and Tungsten Inert Gas (TIG) Hybrid Welding of Stainless Steel
M. Moradi, M. Ghoreishi and M.J. Torkamany

In the present study the Nd:YAG laser-tungsten inert gas (TIG) hybrid butt joint welding parameters of stainless steel 1.4418 have been investigated by coupling a pulsed Nd:YAG laser with a continuous wave (CW) TIG source. The experiments were performed based on the response surface methodology (RSM) as a statistical design of experiments approach to investigate the effect of parameters on the response variations, and achieve the mathematical equations to predict the new results. Welding speed (1 to 5 mm/s), TIG current (90 to 130 A) and distance of heat sources (1 to 5 mm) were assumed as the input process variables while the weld surface width, weld seam area, and weld penetration were considered as the process responses. Analysed by statistical techniques, the results indicated that the welding speed is the most important parameter among all parameters with a reverse effect on process outputs. Besides, TIG current has a direct influence on all investigated responses. The paper invokes the desirability approach optimization technique to achieve the best geometrical dimensions of weld profiles and validating the theoretical results using the experimental tests. Once the optimum settings are considered, a tensile test was also conducted.

Keywords: Nd:YAG laser, tungsten inter gas (TIG) welding, hybrid welding, design of experiments (DOE), response surface methodology (RSM), weld bead profile

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