Experimental Analysis of Welding Parameters of Welded Austenitic Stainless Steel (AISI 316L) by TIG Welding

Abstract

Tungsten inert gas (TIG) welding is type of arc welding with area of applications in food industry, pharmaceutical industry, chemical plants, marine, aerospace, medical devices, and implants, etc. TIG welding process involve several parameters. Many parameters are controllable by the operator, and these parameters have a direct or indirect impact on the microstructure and mechanical properties of the joints. In the present study, three TIG welding parameters, arc current, voltage, and shielding gas flow rate, were changed up to three levels and their effects on surface roughness, hardness, tensile strength, and microstructure were investigated. “Experiments were carried out on a 3 mm thick plate of austenitic stainless steel AISI 316L utilizing a TIG welding equipment and were designed according to Taguchi L9 orthogonal array (OA). Experimentation was conducted two times by using two different filler material, ER 316L and ER 308L. For each single response, input parameters were optimized, and optimum parameters were determined. The analysis of signal to noise (S/N) ratio and analysis of variance (ANOVA) were also used to examine the results. It was observed that each input parameter has influence on the response. For 316L/ER316L welds, Minimum surface roughness was obtained by using parametric combination of arc current 125 A, voltage 16 V and shielding gas flow rate 12 L/min. Optimum hardness was obtained by using parametric combination of arc current 125 A, voltage 16 V and shielding gas flow rate 9 L/min. Optimum UTS was obtained by using parametric combination of arc current 100 A, voltage 16 V and shielding gas flow rate 9 L/min. For 316L/ER308L welds, Minimum surface roughness was obtained by using parametric combination of arc current 125 A, voltage 18 V and shielding gas flow rate 12 L/min. Optimum hardness was obtained by using parametric combination of arc current 125 A, voltage 20 V and shielding gas flow rate 9 L/min. Optimum UTS was obtained by using parametric combination of arc current 100 A, voltage 18 V and shielding gas flow rate 6 L/min. The results were also verified with confirmation tests and a good agreement was found between the predicted and measured results. The microstructure examination shows that dendritic lathy δ-ferrite structure, fine and coarse δ-ferrite structure is present in weld zone of different samples.”