Substrate design-based control of the residual distortion in directed energy deposition additive manufacturing

In this study, the substrate design-based method of controlling the residual distortion in directed energy deposition additive manufacturing (DED AM) is proposed, in which the stiffness weakened interval is formed by designing long strip holes in the substrate. The effects of the designed substrates are studied using the sequentially coupled thermal-mechanical model. It is found that by rapidly releasing the thermal distortion through the designed stiffness-weakened substrate, the residual distortion of the DED AM product can be decreased by more than 60%. In the design of the stiffness weakened interval, a definition of the configuration ratio is adopted to study the design parameters of the long strip holes on the release of the thermal distortion. When the length coefficient and the spacing coefficient is designed between 0.25 and 0.35 and lower than 0.2, respectively, the residual distortion of the DED AM as-built sample can be decreased by 75%-85% without the extra distortion caused by the excessive decrease of the stiffness of the substrate. The simulated results were indirectly verified by the experimental data. This paper provides a new controlling method of the residual distortion in the laser DED AM product by designing the stiffness-weakened substrate.