Effect of welding parameters on bead geometry and microhardness in GMAW: A statistical approach

In Gas Metal Arc Welding (GMAW), the quality and performance of the welded joints can be severely affected by the bead geometry and the associated properties of the materials. Through the use of Analysis of Variance (Anova), this study provides an experimental and statistical analysis of bead width, bead height & microhardness. Welds were deposited on mild steel plates by controlling the voltage, wire feed rate, and torch travel speed with the help of the ABB IRB 1520 robotic welding machine and KempArc DT 410L welding power source. Post-deposition, the welds were characterized on the basis of microstructure observation, which was performed using the scanning electron microscope (SEM), measurement of bead dimensions using the ImageJ program, and a hardness test with the Vickers indentation technique. The collected data were analyzed to determine the effect of each process variable, along with their interaction, on the specified response parameters using ANOVA. The results show that the process variables controlling the input of heat to the welding pool play a major role in determining bead geometry. The bead geometry is greatly influenced by the voltage and wire feed rate, while torch speed has less statistical significance. On the other hand, microhardness depended on the thermal history and cooling rate. The results prove that this statistical approach is an efficient method to study weld responses and for optimizing parameters without making a significant number of experiments.