Impact of Build Plate Packing and Preheat on the Grain Size Evolution in Powder Bed Fusion – Electron Beam of Metals

Additive manufacturing (AM) relies particularly on the precise control of thermal paths to achieve desired microstructural and mechanical properties of the processed material. Complex geometrical shapes often associated with AM result in varying cross sections and consequently fluctuating energy inputs, which can cause localized differences in thermal history that influence material response. The present work explores the impact of variations in thermal history during the AM process on the final properties of built components. In this research, the influence of scan area and preheat on the material’s properties is investigated. The number of specimens on the build plate was altered without changing the process parameters to examine how scan area affects overall process temperature and microstructure. Additionally, using the same build layout and melt parameters, the preheat step was varied to explore further impact on final microstructure. The results show that changes in the number of built specimens significantly impact the energy input, build chamber temperature, grain size, and material strength. Although adjusting the preheat also led to changes, the effects were less pronounced. These findings highlight the importance of understanding and controlling thermal conditions in AM processes to ensure consistent material properties and prevent unexpected component failures.