Parametric analysis of fibre laser beam welding of copper & SS 304

Abstract

Copper and stainless-steel joints have a wide range of applications due to their excellent combination of strength and ductility, electrical and thermal conductivity, and excellent heattransfer capability, such as fuel lines, brake systems, and electrical connections in the automotive industry, refrigeration units, aircraft components, missile systems, space vehicles, electrical transmission systems, electronic components, and so on. The current work used statistical design of experiments to conduct experimental examinations of continuous wave fibre laser beam welding of 1 mm thick commercially pure copper and stainless-steel grade 304 in butt configuration. Regression models are used to establish the relationship between process parameters such laser power, scanning speed, defocus distance, number of passes, & argon gas pressure and output responses like the width of the fusion zone and size of the heat impacted zone for both Cu and SS 304. ANOVA is used to calculate the percentage contributions of the most important process parameters and their optimum ranges on the output responses. It has been found that the welding process depends largely on the laser power, scanning speed, and defocus distance. The width of the fusion zone is also positively impacted by laser power, while all other parameters have a negative effect. While scanning speed and defocus distance have a detrimental effect on the width of the copper's heat-affected zone, laser power, the number of passes, and gas pressure have a favorable effect. The heat affected zone width of SS 304 is similarly affected positively by laser power and number of passes, while negatively by scanning speed, defocus distance, and gas pressure. The efficiency of the shielding gas is demonstrated by the decrease in the occurrence of longitudinal cracks caused by the production of brittle intermetallic compounds. ANOVA demonstrates the generated model's suitability in terms of accuracy. To achieve the best weld quality at the best process parameter setting, a single and multi-objective desirability function-based optimization technique is used. A comparison of optimization results obtained from PSO, TLBO and GWO is also carried out. The created model was found to be in good agreement with the outcomes of the validation experiment. The optimal parameter values are also used to create a set of samples for tensile and micro-hardness tests.