Neutron Diffraction Characterization of Bulk Residual Stress in Vibration-Assisted Wire Arc Additive Manufacturing of Nickel Aluminum Bronze

Wire arc additive manufacturing (WAAM) is a rapidly growing field offering fast, affordable, near-net-shape fabrication of large components. However, WAAM suffers from anisotropic microstructure and high residual stresses that can lead to distortion and fatigue failure. Nickel Aluminum Bronze (NAB) is a prevalent marine alloy explored for WAAM fabrication of propellers. Vibration-assisted WAAM (VA-WAAM) improves the anisotropic microstructure of WAAM, but its effects on residual stress remain unexplored. This work investigates VA-WAAM as a method for engineering the bulk residual stress distribution in NAB thin wall samples.

Samples consist of ERCuNiAl wire deposited onto C95800 NAB substrates using a WAAM system with an ABB IRB 2600ID robot and Lincoln PowerWave R450 power supply. We compare a baseline WAAM build to a VA-WAAM build made with an ultrasonic transducer (20 kHz, 8 μm amplitude, 2 kW) applied to the substrate during deposition. Bulk residual stresses were characterized via neutron diffraction at the HFIR NRSF2 instrument with a 3 mm³ gauge volume, measuring longitudinal, transverse, and normal stress components along the wall centerline. Comparative results and implications for VA-WAAM as a stress engineering strategy will be presented.