Tailoring the energy input to optimize the build quality, microstructure and mechanical properties of H13 steel in electron beam powder bed fusion

The additive manufacturing (AM) of tool and mold components is increasingly adopted for its design flexibility and rapid prototyping advantages. Nevertheless, the broader application of is challenged by process-induced imperfections such as residual stresses, micro-defects, and retained austenite, which can compromise mechanical performance. This study investigates the role of energy input in regulating quality and microstructure of H13 steel fabricated via electron beam powder bed fusion (EB-PBF). Results indicate that the relative density first increases with energy input, reaching a peaking of 99.3 % at 40 J/mm 3 , beyond which it declines due to excessive evaporation and resultant porosity. The microstructure consists of martensite and nanoscale carbides, exhibits excellent mechanical properties, achieving a tensile strength of 1681.2 ± 34.4 MPa and an elongation of 7.2 ± 0.3 %. With increasing energy input, microstructural evolution involves grain coarsening and enhanced carbide precipitation. Moreover, the crystallographic texture transitions from a strong [110]<001> cubic orientation aligned with the build direction to a more randomized state. This microstructural response is attributed to the sustained high-temperature environment in EB-PBF, which mitigates thermal gradients during solidification and reduces the energy barrier for phase transformations driven by fluctuations in energy input. These findings offer valuable insights for microstructural control and process optimization in the pursuit of high-performance H13 steel components via EB-PBF.