ANALYSIS OF MECHANICAL BEHAVIOR OF TIG WELDED AISI321 AUSTENITIC STAINLESS STEEL PLATE

Mechanical Engineering

Welding is used as a fabrication process in every industry large to small. It is a principal means of fabricating and repairing metal products. The process is efficient, economical and dependable as a means of joining metals. After the discovery of the electric arc in 1800 by Humphry Davy, arc welding developed slowly. C. L. Coffin had the idea of welding in an inert gas atmosphere in 1890, but even in the early 20th century, welding non-ferrous materials like aluminum and magnesium remained difficult, because these metals reacted rapidly with the air, resulting in porous and dross-filled welds. In present study Experimental investigation has been carried out for TIG welding on austenitic stainless steelAISI321Material. An austenitic stainless steelAISI321, similar to SS 304 but stabilized with Titanium to avoid inter-granular corrosion. It has a good Weld ability and is used for exhaust stacks and manifolds, pressure vessels, large mufflers for engines, expansion bellows, stack liners, thin wall tubes etc where no post heat treatment of welds is desired.Response surface methodology used for analysis of AISI321 material for ultimate tensile strength, hardness. The input parameters are Weld current, voltage and flow rate. Selection of process parameters are based on the knowledge gained from the literature survey, weldingbrochures, specification of electrodes andvaluable discussion with industrial experienced persons.The total level are varying in five steps. ANOVA analysis carried out to analyze parametric effect for hardness and ultimate tensile strength. Percentage contribution calculated for each response with input parameters. Microstructure also varified for opimized parameters at weld zone , HAZ and base metal. Micro structure analysis shows substantially defect free AISI321 austenitic stainless steel .Optimization carried out using GRA and MOORA method. It is observed that the both method gives almost same set of process parameter for optimize the response.

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