Effect of Layer Thickness in Laser Powder Bed Fusion of HWTS 50 Hot Work Tool Steel

This work optimises and analyses the processing of a new lean tool steel (Osprey® HWTS 50), using laser powder bed fusion (PBF-LB) at 80 °C preheating and different layer thicknesses (20 µm vs. 40 µm). Full density is reached via a higher volumetric energy density (VED) for the lower layer thickness. After optimising contours, reducing surface roughness and ensuring no microcrack formation, the tensile properties are rather comparable in both cases (UTS ∼ 1500 MPa, elongation ∼ 10–12%). However, yield strength, hardness and residual stresses are slightly higher for the lower layer thickness. The geometrical freedom for intricate features is nevertheless comparable.