Experimental Study on Heat Input and Its Effect on Mechanical Properties of MIG Welded Joints

The present study investigated the effect of heat input on the mechanical properties and weld quality of MIG (Gas Metal Arc Welding) welded joints through experimental and statistical approaches. Mild steel specimens were welded under different combinations of welding current, voltage, welding speed, and shielding gas flow rate to generate varying heat input conditions. The influence of heat input on tensile strength, hardness, bead geometry, and welding defects was systematically evaluated. Experimental results indicated that moderate heat input produced superior weld quality, improved penetration, and enhanced mechanical properties, whereas excessive or insufficient heat input resulted in defects such as porosity, cracks, undercut, and lack of fusion. Statistical tools including Taguchi Design of Experiments, ANOVA, regression analysis, and signal-to-noise ratio analysis were employed to identify the most significant process parameters and determine optimal welding conditions. The optimized parameter combination achieved maximum tensile strength, improved hardness, and reduced defect formation. The study demonstrated that proper heat input control and parameter optimization can significantly enhance weld performance, productivity, and process reliability in industrial fabrication applications.