Influence of Input Parameters and Post-weld Heat Treatment on the Metallurgical and Mechanical Properties of Electron Beam-Welded Thick AISI 409 Ferritic Stainless Steel

During this research work, the impact toughness and tensile strength of the electron beam-welded AISI409 plates were evaluated as a function of varied heat input (low 0.96 kJ/mm and high 1.10 kJ/mm) and after imparting post-weld heat treatment. Ferritic stainless steels are prone to enlargement in grain structure and degradation of mechanical properties on exposure to heating and cooling cycles during welding which results in deterioration in their performance. Results revealed that the base metal possessed coarse ferrite grains which got transferred into columnar and axial grains due to faster cooling rate of electron beam welding. The impact toughness of the specimens extracted from the top region of weld zone, when welded using high heat input, reduced by 46% as compared to the base metal. However, the specimens extracted from the bottom section possessed 83% higher impact toughness as compared to the top section. Further, the post-weld heat treatment resulted in refined microstructure, which increased the impact toughness by 35% and 24% for high heat input and low heat input welded joints, respectively. However, the tensile strength of the specimens extracted from the bottom section improved by 26% as compared to the base metal. Graphical abstract