Residual stress is a critical issue in components produced by Laser Powder Bed Fusion (LPBF), as it can compromise mechanical integrity and dimensional accuracy. This study used Simufact Additive to simulate residual stresses in CoCrMo alloy parts, beginning with a disc geometry previously characterized through experimental X-ray diffraction (XRD). The simulation closely reproduced the measured stress patterns and the effects of heat treatments at 750 °C and 950 °C, validating the model’s accuracy. This validated approach was then extended to a Schwarz diamond TPMS lattice (12 × 12 × 12  mm3, 4 mm unit cell size). The lattice exhibited lower residual stress than solid parts, although stress concentrations were observed near junctions. Heat treatments at 750 °C and 50 °C led to 95% and 104% reductions in peak stress, changing the nature of residual stress for the 950 °C heat-treated sample. These results demonstrate the utility of simulation tools for optimizing post-processing strategies in architected LPBF structures.