The heat generated by the electric arc is usedto melt and joint the base metal. The traveling speed of theelectrode is controlled by a servo mechanism. In the experiments, the welding power source is provided by a thermalarc AC welding machine (HeroTIG 250P). The shielding gasis argon and the flow rate of the shielding gas is controlled bya valve meter. The base metal is S304 stainless steel plates.A single-pass welding process is performed because thethickness of stainless steel plates is 1.5 mm. Based on theabove discussion, the TIG welding process involves a numberof welding process parameters such as arc gap, flow rate,welding current and welding speed. The quality of the weldsis dependent on the selection of the welding process parameters. In the present study, TIG welding experiments arecarried out by varying the arc gap in the range of 1.7–2.6 mm, the flow rate in the range of 8–11 l/min, the weldingcurrent in the range of 40–55 A, and the welding speed in therange of 13.5–15.0 cm/min.To evaluate the quality of TIG welds, the measurements ofthe weld pool geometry are performed (Fig. 2). In this study,the front height, front width, back height and back width ofthe weld pool are used to describe the weld pool geometryand measured by a 3D-Hommelewerk profilometer. Basically, weld penetration at the back face of the base metalmust be achieved to ensure the weld strength. The frontheight, front width, back height and back width of the weldpool have a smaller-the-better quality characteristic.