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.”
