Additive Manufacturing of Tool Steels

Additive manufacturing of tool steels encompasses a family of layer-wise processes that transform metallic powders into complex near-net-shape dies, moulds and tooling components. Key techniques include laser powder-bed fusion and laser-directed energy deposition, both of which impose rapid heating and cooling cycles that govern solidification, phase transformations and residual stress. The high solidification rates suppress undesirable phases and produce fine cellular microstructures, while intrinsic heat treatments arise from successive thermal exposures during build-up. Control of process parameters—laser power, scan speed, hatch spacing and baseplate temperature—enables tuning of density, microcrack formation and phase balance between retained austenite and quenched martensite. Alloying elements such as chromium, vanadium and molybdenum segregate to interdendritic regions or precipitate as carbides, contributing to wear resistance and high-temperature strength. The design freedom of additively manufactured tool steels allows for conformal cooling channels and topology-optimised inserts, enhancing thermal management in injection moulding and hot stamping. Computational thermodynamics and in situ diagnostics provide new insights into phase kinetics, while post-processing heat treatments further refine hardness and fatigue resistance. Together, these advances are driving global adoption of additive-manufactured tooling in automotive, aerospace and energy sectors.

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Additive Manufacturing of Tool Steels publication trend

The graph below shows the total number of articles in additive manufacturing of tool steels across all publications each year (not limited to Nature Index journals).

Technical terms

Additive manufacturing (AM): Layer-by-layer fabrication of parts from metal powder or wire feedstock.

Laser powder-bed fusion (L-PBF): AM process in which a laser selectively melts powder layers to form solid sections.

Laser-directed energy deposition (L-DED): AM technique that feeds powder into a laser-generated melt pool to build up material.

Martensitic transformation: Diffusionless phase change from face-centred γ-iron (austenite) to body-centred tetragonal α′-martensite.

Austenite: High-temperature, face-centred cubic phase of iron that transforms on cooling.

Carbides: Hard compounds of carbon with elements such as V, Cr or Mo that strengthen steel.

Intrinsic heat treatment (IHT): In situ tempering effects arising from repeated thermal cycling during AM build-up.

References

1. Microstructure evolution during laser-directed energy deposition of tool steel by in situ synchrotron X-ray diffraction. Additive Manufacturing (2023).
2. Insights into primary carbides and nanoparticles in an additively manufactured high-alloy steel. Acta Materialia (2024).
3. Influence of solidification structure on austenite to martensite transformation in additively manufactured hot-work tool steels. Acta Materialia (2021).
4. Additive manufacturing–assisted conformal cooling channels in mold manufacturing processes. Advances in Mechanical Engineering (2017).
5. Case Study to Illustrate the Potential of Conformal Cooling Channels for Hot Stamping Dies Manufactured Using Hybrid Process of Laser Metal Deposition (LMD) and Milling. Metals (2018).