Effect of Tools Geometry and Dwell Time on Mechanical Properties and Macrograph of Two-Stage Refilled Friction Stir Spot Micro Weld

Department of Mechanical Engineering, University of Indonesia, West Java, Indonesia

Corresponding author: ario@eng.ui.ac.id

Abstract

In this present study, the two independent tools were used in the RFSSW process to joint similar material of AA1100 with a thickness of 0.42 mm using lap joint configuration. Effect of tools geometry and dwell time on mechanical properties, and macrograph was investigated. The joints were successfully obtained with better surface appearance. The micro-hardness variation at 4 group location shows higher than the base metal, while the maximum micro-hardness was obtained at parameter TC-8 at the center of the weld. Macrograph analysis showed the important factor that brings the plug fracture in all combination of parameters. It was the upward bending hook that leads to the crack propagate along the stirred zone to the top sheet, resulted in tear-off the top sheet from the bounded region. Increasing dwell time and tools size will increase the maximum tensile shear load significantly. The best average value of maximum tensile shear load that has been achieved was 561±24 N using the parameter tool C with 8 s dwell time (TC-8).