Professor, Department of Mechanical Engineering, Government Engineering College Thrissur, India

Speech Title: Submerged Friction Stir Welding of AISI 316L Stainless Steel: Microstructural, Mechanical & Corrosion Characterization

Abstract: In the present investigation, rolled sheets of AISI 316L stainless steel with 3 mm thickness were joined in the butt configuration using submerged friction stir welding (SFSW). The welds were made by varying the tool rotational speed from 600 to 1400 rev/min, in steps of 400 rev/min with the other process parameters held constant (welding speed of 50 mm/min, axial force of 12 kN, and tool tilt of 1.5°). The microstructural characteristics of the welded joints were studied by optical microscopy, scanning electron microscopy and electron backscattered diffraction imaging. The results of the experimental studies and analysis reveal that the SFSW joints exhibited overall better joint strength, and the weld made at 1000 rev/min is superior in terms of tensile strength and microstructural features when compared to the base steel. Electrochemical corrosion studies showed that the pitting corrosion behaviour of the base steel and all the weld joints are characterized by a stable pitting potential with no active passive transition behaviour. Also, the pitting corrosion resistance of all the weld joints, especially the weld joint made at 1000 rev/min is marginally higher that of the base steel. In all the cases, no sign of existence of secondary precipitates was observed probably owing to the lower peak temperatures and faster cooling of the weld zone.