Multi-physics modeling for laser powder bed fusion process of NiTi shape memory alloy

Due to its excellent shape memory effect and super elasticity, NiTi Shape Memory Alloy (NiTi SMA) has broad application prospects in aerospace, ship, biomedicine and other fields. Laser powder bed fusion (L- PFB) has proven to be a feasible way to fabricate NiTi with a complex and precise structure. In this study, a 3D transient multi-physics model based on the computational fluid dynamics (CFD) model is proposed, which incorporates the effects of convective heat transfer and radiation heat transfer on the forming quality of parts and mechanical models such as thermal buoyancy. The temperature field and stress field dis-tribution during the L-PBF forming process of NiTi alloy were studied by using this multi-physics model. Furthermore, the influence of different process parameters on the shape of the molten pool was analyzed, and a nonlinear regression equation was proposed to predict the size of the molten pool. The proposed model is verified by experimental results with a prediction error of 3 %-8 %. Both numerical and experi-mental results demonstrate that under the process parameters of P= 125 W and V= 500 mm/s, the shape of the molten pool is stable and the NiTi single track is continuous. This work illustrates the reliability of the established simulation method and provides a timesaving approach to optimize the L-PFB process para-meters of nickel-titanium alloy.(c) 2023 Elsevier B.V. All rights reserved.