Depth Resolved Investigation of Friction Stir Welds Made from AA2024 / AA2024 and AA2024 / AA6082 Using a Spiral Slit and High Energy Synchrotron Radiation

The strain and phase distributions in friction stir welds (FSW) of AA2024-T3 to AA2024-T3 and AA2024-T3 to AA6082-T6 are investigated non-destructively. The measurements are performed using a novel depth resolved strain and phase mapping technique. The technique is based on the use of a focussed high energy synchrotron beam, a novel spiral slit system, and an area detector system. The strain scans across the dissimilar FSW exhibit a strong asymmetry in particular for the longitudinal strain component. A depth resolved strain mapping across the weld shows for the dominant longitudinal strain component variations in depth, especially on the AA6082 side of the dissimilar weld. The variations are significantlty weaker in the AA2024 / AA2024 weld. Results from the strain measurements are related to the depth resolved map of the material distribution in the weld zone.