Optimum welding process parameters investigation for mechanical properties of mild steel welded by GMAW

Abstract

Gas Metal Arc Welding (GMAW) process is the most widely used welding process for structural fabrication industries, owing to its high productivity and ease. This research investigates on the optimum welding process parameters for achieving better mechanical properties of weldment. In order to meet the requirement in terms of both welding efficiency and effectiveness, the Taguchi parametric design methodology and regression analysis is used. Weld Process parameters considered for this research are welding current, welding voltage, shielding gas. The process output characteristics are ultimate tensile strength, hardness and toughness of the weldment. After collection of data from the experimental work, signal to noise ratio were calculated and the optimum level of every process parameters was obtained by using Taguchi method. Subsequently by using the analysis of variance, the significant co-efficient for each input factor on the mechanical properties was determined and regression analysis is carried out for predicting the mechanical properties.In this research, the mechanical properties were obtained by welding of 10 mm Mild Steel IS 2062 thick plates in Gas Metal Arc Welding using Ar+18% CO2, pure CO2 and Ar+5% O2 as the shielding gas mixtures. The optimum tensile strength was achieved in the shielding gas mixture Ar+18% CO2 and also it provides the optimum toughness value. Pure CO2 gives the superior hardness values when compared to other shielding gas compositions. The numerical results reveal that the shielding gas and welding current have significant effect on the mechanical properties of weldment.