Thermal behavior, residual stress, and deformation of thin-walled parts in double electrode arc-directed energy deposition

Abstract

Arc-directed energy deposition (DED) can produce large-scale metal components with high deposition rates. However, large residual stress (RS) and deformation are formed in as-built parts since serious heat accumulation is generated due to considerable heat input, damaging the mechanical properties of deposited parts. This study aims at controlling stress and deformation of as-built thin walls by applying a double electrode arc-DED technique with lower heat input. By introducing an additional branch electrode to divert some current from the main wire, the heat input to deposited layers is reduced. Double electrode arc-DED has the potential to achieve higher deposition rates and lower heat input to deposited layers without compromising the forming quality. The novelty is that how the branch current affects the temperature, RS, and deformation of walls in double electrode arc-DED is revealed by using finite element simulation. A composite heat source model is developed to characterize the thermal effect of the double electrode arc. Experimental tests check the finite element model's effectiveness. The simulation results are in good agreement with the experimental results. Compared to conventional gas metal arc-DED, the high-temperature zone on as-built layers shrinks, and the melt pool's peak temperature and length decrease in double electrode arc-DED. As the branch current increase from 0 to 105 A, the maximum longitudinal RS on as-built layers decreases from 292 to 265 MPa, and the maximum deformation on the substrate reduces by 1.5 mm, indicating that introducing a branch arc can effectively reduce the heat input, RS, and deformation in arc-DED. This study provides valuable guidelines on regulating RS and deformation in arc-DED from the perspective of decreasing heat input to as-built layers.