Influence of MIG Welding Process Parameters on Tensile Properties of Mild Steel.

Metal Inert Gas welding (MIG) is a widely used welding method for mild steel (low carbon steel) in industry due to its high weld quality, good penetration and comparatively low investment. It is an arc welding process wherein coalescence is produced by heating the job with an electrical arc struck between a filler rod and the job. A Shielding gas (argon, carbon dioxide) is used to avoid atmospheric contamination of the molten weld pool. A filler material is added for joining the work piece by MIG welding. Many researchers investigated on different welding process parameters on mechanical & microstructural characteristics. Some researchers used the welding speed, welding current welding voltage, number of welding passes & work peace thickness for stainless steel, naval grade steel & aluminum. But the shielding gas flow rate & gas mixture also important factor which affects mechanical properties of mild steel. For this study, process parameters such as welding current, gas flow rate and gas combination used in the range 170-210A, 13-17 Lit/min & 0-100 % of CO2 respectively. The material used E-250 grade mild steel with 12 mm thickness. The effect of the welding parameter is investigated by designing the experiments using central composite matrix. Using the data generated by the experimentation, an empirical relation is obtained for tensile strength. The optimum value of tensile strength 356 N/mm² is observed at 190A welding current, 15 Lit/min gas flow rate & 50% CO2+50% Argon gas combination.

Index Terms—Co2 Welding, v-butt Welds, welding current, gas flow  rate, Gas combination, Tensile strength.