Tailoring Laser Powder Bed Fusion and Post‐Processing Parameters for JIS SKD61 Tool Steels: Surface Roughness, Microstructure, and Mechanical Properties

This study evaluates Laser Powder Bed Fusion (LPBF) parameter selection for JIS SKD61 (AISI H13 equivalent) hot‐work tool steel using a Taguchi L9 design and ANOVA, targeting surface roughness, hardness, and tensile strength. While LPBF studies frequently report AISI H13, a statistically structured assessment for SKD61 is scarce. Laser power, scan speed, hatch spacing, and layer thickness were systematically varied to identify a stable processing window and the most influential factors. An optimal volumetric energy density of 141.67 J/mm 3 balanced melt stability and defect suppression, enabling consistent track overlap and reduced lack‐of‐fusion porosity over the build area. Specimens produced under the selected condition were tempered at 600°C to relieve residual stress and tune the martensitic microstructure. Relative density was quantified from metallographic cross‐sections, and surface roughness (Ra) was measured per ISO 4287. Microstructural evolution was examined by SEM and phase changes were assessed by XRD, revealing tempered martensite with carbide precipitation after heat treatment. The selected process, heat treatment route, achieved 99.78% relative density and Ra of 9.55 µm, together with improved hardness and tensile strength compared with non‐tempered builds. Compared with the as‐built condition (UTS = 1342.58 MPa), tempering at 600°C increased UTS to 1888.13 ± 177.24 MPa. These results demonstrate that LPBF‐processed SKD61 can meet property requirements for hot‐work tooling, including die‐casting dies and injection mold inserts.