Use of Neutron and Synchrotron X-ray Diffraction for Non-destructive Evaluation of Weld Residual Stresses in Aluminium Alloys

Abstract

A full three-dimensional residual stress tensor was determined through a combination of neutron and synchrotron X-ray diffraction in a MIG welded Al2024 plate. The plate was first measured by synchrotron X-rays to determine the strain in the longitudinal (LD) and transverse directions (TD). Then the same plate was measured by pulsed neutrons for the transverse and normal strain directions. The stress-free lattice reference (d₀) across the weld was obtained by measuring a comb sample of insufficient constraint to hold an internal residual stress field. The point-to-point corrected strain data of the three principal directions obtained was then combined to calculate the full three-dimensional residual stress tensor. The comparability of the processes was confirmed by comparing the strain observed in the transverse direction. The combination of these two different experiments enabled determination of a full through-thickness stress map across the weld.