Influence of Build Plate Preheating on the Cell Structure in Stainless Steel 316L Produced by Laser Powder Bed Fusion

Abstract This study investigates the effects of a preheated build plate in laser powder bed fusion on the microstructural evolution of stainless steel 316L, with a particular focus on the cell structure. The work includes scanning and transmission electron microscopy characterizations as well as multiphysics-based deposition modeling. Our findings reveal that preheating temperature is a key factor controlling the microstructure. As the preheating temperature increases, the cooling rate during printing decreases, leading to pronounced changes in the cell structure. Specifically, the cell structure remains largely stable up to 500 °C, whereas preheating to 800 °C leads to a significant increase in the cell size by about 60 pct, as well as a significant decrease in the overall dislocation density. Furthermore, preheated printing results in a microstructural gradient along the building direction due to self-annealing, altogether highlighting preheating printing as an effective strategy for microstructural control.