Testing, characterization and numerical prediction (uni-axial tension and bend test) of Double-side TIG welded SS321 plate for pressure vessel application

Abstract

This study reports the welding of SS321 nuclear grade stainless steel employed for pressure vessel industries using the novel Double-side tungsten inert gas (DS-TIG) welding. The optimization technique (Taguchi-based Grey relational analysis (GRA)) used in this research will give firsthand knowledge to the industry concerning the process variables to produce quality weldments using the DS-TIG welding method. The optimized combination of input variables was noted to produce a butt joint with SS321 plate having 6 mm thickness: Arc length (Al) 3 mm, Arc current (I) 220 Amps, and Traverse speed (S) 120 mm/min. The Analysis of variance (ANOVA) table was created to estimate the significance of the input process variables in the weldments. The impact of process variables on the Depth of penetration: DoP and Bead width: BW in relation to the heat input was evaluated. The microstructural features and mechanical integrity of the DS-TIG weldment made with the optimized combination of input process variables were analyzed utilizing Optical microscopy, Electron back scattered diffraction (EBSD), Tensile, Hardness, Impact, and Bend tests. A Finite element (FE) model of uni-axial tension and bend test was developed to predict the tension strength (base and weld metal) and stress distribution during bend test of DS-TIG specimen. A good agreement between the experimental and predicted results was noticed (error less than 5%) in terms of stress vs. strain plot (uni-axial tension) and load vs. displacement plot (bend test).