Annealing Heat Treatment Effect on the Residual Stresses in Hot-Extruded Aluminum Alloy Rods with High Cross-Sectional Reduction

Abstract

In this study, residual stresses in hot-extruded Al-6061 rods with different cross-sectional reduction were investigated using the contour method. The contour method was used to provide a twodimensional map of residual stresses. The residual stresses were evaluated along the radius of the rods with different cross-sectional reduction before and after annealing heat treatment, and the uncertainty of the contour method was estimated. The results indicate that in the extruded rods with high reduction of diameter, tensile residual stresses are generated in the rod core, which are balanced along the rod radius by compressive residual stresses at the surface. A decrease in the cross-sectional reduction or the rod diameter increase results in rise of residual stresses. The annealing heat treatment reduces residual stresses and creates a symmetrical balance between tensile and compressive residual stresses. The countour method application revealed that maximum and minimum uncertainties occurred at the rod center and perimeter, while the latter one had a greater effect on the residual stress estimation results.