Characterization and optimization of duplex stainless steel welded by activated tungsten inert gas welding process

Novel perception of Tungsten Inert Gas (TIG) welding is Activated TIG (A-TIG) which has potential to enhance the weld penetration. Present work focuses on comparison of TIG and A-TIG welding process performed on 2205 Duplex Stainless Steel (DSS). By varying welding current, torch speed and flux systematic experiments are performed to analyse the effect on weld morphology, microstructure and mechanical properties of welded joints. Experiments results indicated that oxide flux (TiO2, SiO2 and Cr2O3) increases the weld penetration as well as exhibited the higher mechanical strength of weld metal. To improve and enhance the performance of weld, identification of adequate welding conditions (optimum variables) are very essential. For predicting the responses (depth of penetration, bead width, tensile strength and microhardness) mathematical models are generated for given set of input variables using Response Surface Methodology (RSM). Multi-objective optimized responses depth of penetration, bead width, tensile strength and microhardness having 6.23 mm, 7.58 mm, 775 MPa, and 322 HV respectively, are predicted at the 201A welding current, 140 mm/min torch speed and SiO2 flux. Conformity test results are in well agreement with the model predicted values. Hence, the proposed optimized framework can be used in A-TIG welding application in industry.