Determination of Residual Stress in Additively Manufactured 316L Stainless Steel Benchmark Parts Through Synchrotron X-Ray Diffraction and Neutron Diffraction

Additive manufacturing (AM) of parts is typically associated with the generation of high residual stresses because of repeated exposure to high thermal gradients. Non-destructive means of mapping the residual stresses are required for optimising these processes and/or mitigating such stresses by thermal treatments. However, the reliable determination of residual stress in AM parts remains challenging. Here, neutron diffraction, as well as energy- and angle-dispersive synchrotron X-ray diffraction have been used to map the residual stress within a laser powder bed fusion (LPBF) additively manufactured stainless steel 316L arch. The arch was designed by the EASI-STRESS project as a residual stress benchmarking exercise in order to compare different residual stress analysis techniques. Residual stresses were determined along two scan lines deep within the bulk of the component. The results for the different neutron and synchrotron instruments are found to broadly agree with a standard deviation of 50 MPa or better, as well as with those predicted by an inherent strain finite element model. The results show near-yield level residual stresses and suggest that both synchrotron X-ray diffraction and neutron diffraction can be used to reliably determine the residual stress in LBPF parts.