STUDY OF MECHANICAL CHARACTERISTICS OF WELDED JOINTS OF DISSIMILAR AUSTENITIC STEELS SS 202 AND SS 304 BY COLD METAL TRANSFER WELDING PROCESS

Abstract

Welded joints of dissimilar stainless steel sheets have many industrial applications due to their cost effectiveness, light-weight, and high efficiency. Thin austenitic stainless steel sheets of different thicknesses are extensively used in the automation industry. Conventional welding techniques due to their high heat input and high spatters have always posed problems such as burn-through and distortion for welding these joints of thin austenitic steels. The CMT welding technique is effectively used for the joining of thin sheets due to its characteristics of lower distortion rate and low heat input. In this research work, austenitic stainless steels of grade SS 202 and SS 304 of thickness 1.2 mm and 2 mm respectively were welded by CMT welding technique and studied the mechanical characteristics of dissimilar stainless steel joints. Taguchi L9 optimization technique was used to find the optimized process variables for obtaining the maximum tensile strength. The maximum tensile strength of dissimilar joint welded at 115 A current, 4 mm/s welding speed, and 10% arc length correction factor was found to be 291 MPa. The maximum micro-hardness value of the weld zone was achieved and the lower value was observed in the heat-affected zone (HAZ). The X-ray diffraction (XRD) technique was utilized to detect the residual stresses of the welded joint. The residual stress was observed in compressive nature in the weld zone and base plate and of tensile nature in the heat-affected zone (HAZ). CMT welding process can produce high strength dissimilar austenitic steel joints of different thicknesses.