The optimization of residual stress in arc bridge Hastelloy X components fabricated by Laser Powder Bed Fusion

Laser Powder Bed Fusion (L-PBF) has attracted tremendous interest in various fields. However, detrimental residual stresses inevitably form inside the as-fabricated components due to the inherent complex thermal history and ultra-high solidification rate in the L-PBF process. In this study, the formation mechanisms of residual stress during L-PBF of Hastelloy components and the strategies to reduce them were investigated. Components with simple block geometry were first fabricated with different deposition strategies, i.e., scanning island size and rotation angle. The microstructure and residual stress of these samples were characterized. The optimal deposition strategy was then used to deposit the arc bridge components with complex geometry. The results clearly show that different deposition strategy is needed for components with complex geometry due to the change in cross-sectional area and the different heat transfer behavior between the new deposition layer and the previously deposited solid layer. Finally, the arch bridge samples with no warping deformation were achieved by optimized random scanning strategies and crossline scanning strategies. The results obtained in this study thus provide a theoretical basis for tailoring residual stress during L-PBF of complex components.