Integrated framework of multi-physics mechanism models for gas-powder flow, molten pool evolution and part deformation in high alloy steel additive manufacturing process

Multi-physics numerical models for metal additive manufacturing (MAM) could replace the expensive trial-and-error experiments, reveal the mechanisms of printing process, and provide an effective means of optimizing process parameters and mitigating part defects. However, the existing simulations of MAM process seldom consider the coupling effects between multiple recursive processes. There is an urgent need to overcome the dilemma of limiting MAM process simulation to a localized single sub-process. For directed energy deposition (DED) additive manufacturing process, the integrated simulation framework proposed in this study consists of a gas-powder flow model, a heat and fluid flow model, and a sequentially coupled thermal-mechanical model, which can be used to predict the feedstock feeding process, the evolution of molten pool, and the residual deformations of metal part, respectively. The accurate results of the three recursive sub-processes can be obtained by delivering the validated parameters between models. Corresponding experiments are conducted to verify the accuracy of the integrated framework based on 12CrNi2 alloy powders. The deviation of the predicted focal distance of powder streams is 5.14 %, and the deviations of the predicted molten pool height and width are all less than 8.5 %. The integrated framework could rapidly and accurately predict the residual deformation tendency and the position where the maximum deformation occurs. For single-track and eight-layer line deposition, the deviations of the predicted maximum deformation are all within 0.1 mm. The integrated framework could efficiently provide accurate and comprehensive solutions for optimizing DED process.