Synchrotron investigation of heat treatment effects on the 3D residual stress distribution in laser powder bed fused AlSi7Mg alloys

• AlSi7Mg (A357) cubes were produced by PBF-LB and subjected to different heat treatment routes. • For the first time, high resolution synchrotron diffraction was used to build 3D maps of residual stresses in bulk samples. • The effects of heat treatment time and temperature on the stress distribution was resolved. • We provide valuable insights into the optimal schedule to reduce residual stresses in AlSi7Mg PBF-LB parts. For the first time, we utilized synchrotron diffraction to determine 3D maps of residual stresses across the entire volume of thick AlSi7Mg alloy prisms produced by PBF-LB. Samples were subjected to different heat treatment processes: direct aging (T5), solution treatment, and solution treatment followed by aging (T6). The T6 heat treatment resulted in the lowest residual tensile strains, while the T5 treatment resulted in significantly higher residual strains. Maximum residual stresses decreased from the as-built condition to the T6 heat-treated specimen. Although the T5 condition provides greater strength, it also retains higher tensile residual stresses near the surface, which can negatively affect fatigue properties.