SELECTION OF APPROPRIATE PROCESS PARAMETERS FOR ENHANCEMENT OF PENETRATION IN TIG WELDING OF 304H STAINLESS STEEL FLATS: AN AHP-BASED APPROACH

Weldability is a critical factor in the fabrication of various grades of stainless steel used in industries. Tungsten Inert Gas (TIG) welding, known for its precision and high-quality results, is frequently employed in industrial applications. However, one of the common challenges with TIG welding is achieving adequate penetration of weld joints, despite the flexibility to modify welding parameters. A suitable combination of welding parameters such as current, inert gas flow rate and root gap can increase heat input and improve penetration depth, leading to a significant enhancement in the quality of weld joints and its productivity. This, in turn, ensures better performance and long-term reliability. In this work, the welding process of 304H austenitic stainless steel is tried to be optimized, that is known for its strength and corrosion resistance in boiler components. The experiment is designed using Response Surface Methodology (RSM) with Central Composite Design (CCD), considering three factors: heat input, root gap and gas flow rate. Each factor is tested at three different levels to understand their effect on the quality of the welds, aiming primarily for full penetration, which is crucial for creating a strong joint. A total of 14 samples of 8mm thick 304H stainless steel plates, each measuring 50 mm by 50 mm, are welded using Gas Tungsten Arc Welding (GTAW), popularly known as TIG welding, with similar filler material to improve the overall weld quality. In this study, the Analytical Hierarchy Process (AHP), a multi-criteria decision-making tool, is employed to validate the optimal values determined. The results obtained from the research align well with the AHP results.