Influence of nozzle structure on the consumption of shielding gas in the gas metal arc welding process

Abstract

To reduce the consumption of gas metal arc welding shielding gas and improve welding quality, three spiral-diffusion nozzles with different structures were designed in this study. The four evaluation indexes of the flow field quality of shielding gas were determined by analyzing the protective airflow field with the computational fluid dynamics simulation method. Isight software was used to optimize the multi-objective parameters of the three spiral-diffusion nozzles with the self-adaptive mutation genetic algorithm. Combined with the computational fluid dynamic simulation results, the optimized value of each nozzle and the percentage of parameters such as gas reduction were obtained. Three new double-helical spiral-diffusion stainless nozzles were created using 3D printing, and the gas metal arc welding of the Q235 and A36 steel plates was performed using 80% Ar + 20% CO2 mixed shielding gas with three nozzles. The tensile test and impact test were conducted to inspect tensile strength and impact toughness, and the hardness and average grain grade of microstructures in the weld seam were analyzed. The experimental results were consistent with the optimization simulation results. In terms of welding quality, compared with the shielding gas consumption of the conventional nozzle, that of the optimized spiral-diffusion nozzles I, II, and III could be reduced by 29.22%, 33.19%, and 27.31%, and the effective protection range could be increased by 34.53%, 19.79%, and 19.69%, respectively.