Influence of Tool Geometry in Friction Stir Welding

Abstract

Abstract In this article we highlight the results of a recent study undertaken to understand the influence of tool geometry on friction stir welding (FSW) of an aluminum alloy with specific reference to microstructural development, defect formation, and mechanical response. The welding trials were made on 4.4 mm thick sheets using tools made of die steel and having different diameters of the shoulder and the pin, and the profile of the pin. Throughout the welding operation, the rotational speed, traverse speed, and tool axial tilt were held constant at 1400 rpm, 80 mm/minute, and 0 degrees, respectively. For a shoulder diameter of 20 mm and a pin diameter of 6 mm, the severity of defects in the weld was found to be the least and the resultant tensile strength of the weld was high. For the welds that were made using a tool having a shoulder diameter of 10 mm and a pin diameter of 3 mm the tensile strength of the weld was the least since the degree of defects observed were higher. Keywords: Aluminum alloysButt jointsDefectsFracture characteristicsFriction stir weldingGrain growthHeat affected zoneHeat inputMechanical propertiesMicrostructureOver-ageingPrecipitation hardeningTrans weld tensile testingTool geometryWeld base material interfaces ACKNOWLEDGMENTS Authors would like to thank Mr. G. M. Gururusamy and Mr. P. Srinivasarao of LPSC/ISRO, Bangalore for providing material and their support. Authors also wish to thank Mr. K. B. Teggi, Mr. K. Manoharan, Mr. V. Ganganna, and Mr. V. Saravana of CPDM/IISc for their help in tool making and sample preparation. Notes *AFW = Away from the weld.