Experimental Investigation and Finite Element Simulation of the Microstructural Evolution in AA6082 Friction Stir Welded Joints

The microstructural evolution of components subject to friction stir welding (FSW) significantly affects their mechanical properties, service quality and longevity. During the welding process, temperature, strain and strain rates intrinsically influence both grain size and the structural characteristics of joints. However, the correlation between materials, process parameters and the final microstructure remains unclear. The aim of this study is to develop a finite element method (FEM) simulation of FSW that incorporates microstructure prediction of welded components. The FEM simulation was developed using the commercial software package DEFORM-3D. Experiments were conducted by processing AA6082-T6 components with various feed rates and cooling conditions. Validation of the developed simulation was carried out by comparing numerical and experimental peak temperatures in distinct areas of the welded sample, with a forecasting error of less than 10% consistently achieved. Simulation outcomes provide novel insights into the impact of FSW parameters on microstructural evolution, with prediction of the final grain size aligning with experimental data in terms of both the extent of the recrystallized zone and grain size.