The Investigation of the Triaxial Residual Stress in the Friction Stir Welded Lap Joint Using Neutron Diffraction

A detailed study of the complex triaxial residual stress distribution of the double-pass friction stir welded (FSW) lap-joint between two different high strength aluminum alloy sheet materials was conducted. A non-destructive technique known as neutron diffraction was used to measure the internal residual stress distribution in the three principal direction of the lap-joint in the as-welded and hammer peened configurations to determine effects of hammer peening on redistribution of residual stresses across the weld. The residual stress variation across the weld in the transverse direction contained the highest values of tensile stress in all three principal directions. The residual stress in the hammer peened test specimen was in most cases reduced in all three principal directions.