Connecting Residual Stresses with Friction Stir Welding Conditions and Pseudo-Heat Index

Abstract

This study examines the connections between friction stir welding (FSW) parameters, the simple pseudo-heat index (PHI) metric, and the prediction of resultant residual stresses on AA5052-H32 plates. A range of weldments was produced with different tool rotational speeds (283–1732 RPM) and traverse speeds (200–800 mm/min) to produce the same values of PHI with distinctly different FSW conditions. Residual stresses were measured on the surfaces of the welded plates using x-ray diffraction. All of the friction stir welds produced the typical, M-shaped longitudinal residual stress profiles across the weld. The largest tensile stresses were produced for low PHI conditions, which did not fully consolidate the material. For sound welds, increasing traverse speed with fixed rotational speed did systematically increase the residual stresses inside the stir zone. However, the simple metric of PHI was not a good predictor of the stir zone residual stress.