OPTIMIZATION OF WELDING PARAMETERS IN COLD METAL TRANSFER WELDING OF STAINLESS STEELS

Abstract

For better efficiency, manufacturers these days are more interested in using very light weight materials that not only reduces the overall weight of the structure but also enables the use of latest technology. Due to their immense strength, ease in fabrication, Austenitic Stainless Steel grades find their application in wide range of manufacturing industries such as automotive, medical, construction, aerospace. Various problems such as burn through, distortions, spatter and other defects were reported when thin austenitic stainless sheets were welded using conventional arc welding process because of their high heat input. Cold Metal transfer welding is a modern era welding technology for joining of thin sheets as optimum penetration at low heat input and spatter free weld can be obtained. In this research work SS202 samples of thickness 1.58mm have been welded using SS308 filler wire by CMT welding process. Three different levels of Current (80A, 100A, 120A), Welding speed (3mm/sec, 4mm/sec, 5mm/sec), and Pulse dynamic correction Factor (-10, 0, +10) were set as input process parameter. The experiments have been carried out at most optimum parametric combination obtained from Taguchi L9 design of experiment array. The superiority of weld was estimated in the form of three mechanical properties Yield Strength (YS), Ultimate Tensile Strength (UTS), and Percentage Elongation wherein highest value obtained for the three were 379 MPa, 871 MPa, and 65.9% respectively. The experimental data obtained have been optimized by Taguchi’s S/N ratio larger the better criteria. Further, Ultrasonic Assisted CMT Welding have been carried out on same SS202 samples of 1.58mm thickness under same process parameter and result have been compared with responses obtained for CMT welded samples without Ultrasonic vibrations.