Uncertainty analysis of contour method in the hot extruded Aluminum specimens

The contour method is a new approach to measure the residual stress and use to provide a two-dimensional map of residual stresses. In this study, residual stresses were measured in the rods which produced by hot extrusion with high reduction cross section. The rods material was 6061 aluminum alloy and the effect of annealing heat treatment has been studied on the rods. For this purpose, residual stress has been evaluated before and after annealing heat treatment and the uncertainty of the contour method calculated. The results indicate that in the rods that produced by hot extrusion with high reduction cross section, tensile residual stress is created in the rod core and by moving along radius changed to compressive residual stress such that the surface is balanced via tensile and compressive stress. The maximum tensile residual stress is formed on the rod center and performing annealing heat treatment causes to high reducing residual stress. Also the uncertainty investigation determined, the uncertainty was almost uniform on the surface and displacement error and model error sources have a same effect on the uncertainty of contour method.