Experimental Investigations on Welding Characteristics of Mild Steel Using TIG and MIG Welding

Abstract

Mild steel also called plain-carbon steel is the most common form of steel because its price is relatively low  while it provides material properties that are acceptable for many applications, mild steel has a relatively low tensile strength and malleable; surface hardness can be increased through carburizing. This material is also electrically conductive, easily available and flexible in design. It can be machined by using many non-conventional methods like laser cutting, water jet machining and plasma arc machining. Among them plasma arc machining any hard material and to produce intricate shape increases its demand in market. This process is considered a challenging technology compared to its main competitors: oxy-TIG &MIG welding fuel and laser cutting, in particular for cutting of mild steel for thickness 8-40 mm. By considering literature surveys for TIG & MIG welding to parametric optimization and analysis to attain target and optimum results, TAGUCHI method and response surface methodology is employed. For this hypertherm plasma arc source, operating 30-400 A and output voltage between 100-200V is considered. The appropriate orthogonal array has been selected as per number of factors and their levels to perform minimum experimentation. The first part of work targets on finding the optimal combination of parameters which gives the best performance measure. For this TAGUCHI techniques are applied and then ANOVA F-test is performing to check the significance. In second part of project regression equation is generated by using response surface methodology through central composite design scheme to obtain output value with in specified limits without further experimentation. Test is performed to check the significance and errors are compared.