Residual stress reduction in wire arc additively manufactured parts using in-situ electric pulses

Components fabricated in metal additive manufacturing, including wire arc additive manufacturing, undergo complex thermal cycles, resulting in residual stresses and thermal distortions. The present work investigates the effect of applying in-situ electric pulses to the component after the deposition of every layer to reduce residual stresses. The experimental results revealed that electropulsing resulted in dislocation rearrangement/annihilation, thereby decreasing dislocation density. A significant reduction in the fraction of low angle grain boundaries was observed for electropulse-treated samples, indicating a decrease in residual stress. Further, X-ray diffraction results also confirm a reduction in residual stress (24.0–29.4% reduction compared to untreated samples). The method can effectively be used to address specific regions selectively in addition to in-situ reduction of residual stresses in deposited components. Abbreviations: EBSD: electron backscattered diffraction; EPT: electropulsing treatment; EWF: electron wind force; GND: geometrically necessary dislocations; KAM: Kernel average misorientation; LAGBs: low angle grain boundaries; WAAM: wire arc additive manufacturing; XRD: X-ray diffraction