<p>Nowadays, the fabrication industry highly recommends activated flux tungsten inert gas (A-TIG) welding due to its capability in achieving a higher single-pass depth of penetration. The requirement of additional filler material and groove preparation could be avoided for up to 10-12&#xa0;mm plate thickness using A-TIG welding. This leads to an increase in overall productivity. In the current work, 8&#xa0;mm thick IRSM 41 steel plates were joined with A-TIG welding. The process parameters, such as welding current, flux coating density and welding speed, were optimized to achieve the required weld bead geometry by utilizing a central composite design (CCD) of response surface methodology. Weld bead width (WBW), depth/width (D/W) and depth of penetration (DOP) were measured as responses and correlated with the input variables. Mathematical models were created for forecasting the responses corresponding to the given input process conditions. Analysis of variance technique (ANOVA) was adopted for evaluating the adequacy of the generated model. Confirmatory tests were conducted for ensuring the consistency of the responses attained through the generated mathematical models. The confirmatory test results illustrate that experimental and predicted values were in good agreement. The root mean square error values for WBW, D/W and DOP were 0.33, 0.029 and 0.17, respectively. Optical and secondary electron microstructural studies were conducted to understand the grain growth during A-TIG and TIG welding. The mechanical properties of the weldment have been assessed using the hardness, tensile and bend tests. The correlations have been developed between the microstructures and mechanical properties.</p>