Modeling and Simulation of Under-Water Friction Stir Welding of Al 6063 Alloy

Abstract

Friction stir welding (FSW) of aluminum alloys is widely used in aerospace and automotive industries; however, existing studies primarily focus on air-environment welding, lacking insights into underwater cooling effects and thermal behavior. To address this limitation, this study proposes a numerical thermal simulation framework to predict weld-zone temperature distribution and heat flux during underwater FSW of AA6063. A threaded cylindrical H13 tool is used in ANSYS to model frictional and plastic deformation heat generation, with input parameters including contact geometry, axial force, and tool rotational speed. Simulations reveal that underwater cooling reduces peak temperatures by over 20%, with shoulder and pin heat fluxes of (q_s = 4.09  10⁶) W/m², and (q_p = 5.23  10⁵) W/m²,  enhancing model prediction accuracy by approximately 15%. The proposed method enables reliable thermal analysis, guiding future process optimization and underwater FSW applications.