Simulation of annealing process on AISI 316 L stainless steel fabricated via laser powder bed fusion using finite element method with creep

摘要

In the laser powder bed fusion (L-PBF) process, the development of residual stress in as-built components is unavoidable owing to the concentrated heat input and rapid solidification. Thus, the manufacturing of precise components using L-PBF is challenging because of the deformation of the finished products caused by residual stresses. Annealing heat treatment after L-PBF can effectively reduce the residual stress; however, it also reduces the hardness and yield strength of the products. In this study, the deformations of AISI 316 L components fabricated via L-PBF with and without annealing heat treatments were investigated in terms of residual stresses caused by the L-PBF process. In addition, a finite element model was developed for predicting the deformations as well as the evolution of the residual stresses during the annealing process. Cantilever-type residual stress experiments were designed and conducted to quantitatively analyze the evolution of the residual stresses during annealing heat treatments under different conditions. The annealing behavior of 316 L was modeled using the creep material properties. The developed simulation model was further validated using two specially designed components, an auxetic cantilever and a propeller made of 316 L using L-PBF. The developed model could accurately represent the deformations of 316 L components fabricated via L-PBF. In comparison to the deformations measured in the experiments, those estimated by the model showed average error values of only 0.21 and 0.19 mm for the auxetic cantilever and propeller, respectively.