Application of 3D DIC-Assisted Residual Stress Measurements for Friction Stir Welding Weld from Ultrafine-Grained Aluminum

The present study describes a novel approach applying 3D digital image correlation to a hole drilling method to measure residual stresses. Measurements were performed on a friction stir-welded joint made of ultrafine-grained aluminum. The results show that severe plastic deformation did not significantly change the residual stresses, while in the weld’s stir zone they increased to 100 to 200 MPa. The obtained results demonstrate the reliability of the applied residual stress measurement method.