Influence of atomizing gas and pressure on the metallurgical characteristics and environmental performance of K340 tool steel powder produced by vacuum induction melting inert gas atomization

K340 tool steel is widely used in dies and tooling applications requiring high wear resistance, toughness, and durability; however, its availability as powder feedstock for additive manufacturing remains limited. In this study, K340 powder was produced from industrial scrap by vacuum induction melting inert gas atomization, with the aim of assessing key metallurgical characteristics and the environmental benefits of scrap recovery and valorization. Argon and nitrogen were used as atomizing gases at pressures of 40 and 45 bar, and their effects on powder yield, particle size distribution, morphology, flowability, chemical composition, microstructure, and carbon footprint were systematically investigated. Powders in the 45–125 μm range, suitable for directed energy deposition (DED), represented 41.8–54.6% of the atomized material. Argon atomization promoted higher yields in this target fraction, whereas nitrogen atomization resulted in higher apparent density and improved flowability (Hall flow time as low as ∼14.2 s), together with finer solidification microstructures, as indicated by secondary dendrite arm spacing values close to 1 μm in the finest powder fraction (20–45 μm). The chemical composition of the powders remained consistent with the starting K340 scrap, while nitrogen atomization led to measurable nitrogen uptake, particularly in coarser particles. A cradle-to-gate carbon footprint assessment was carried out by comparing scrap-based, typical-grade, and virgin-grade feedstock scenarios. Although atomizing gas and pressure had only a limited influence on batch-level emissions compared to feedstock-related contributions, which dominate the overall carbon footprint, normalization per kilogram of usable powder highlighted the critical role of process yield. The use of industrial scrap reduced the carbon footprint by up to approximately 80% compared with virgin-grade feedstock. Overall, the results demonstrate that vacuum induction melting inert gas atomization can produce DED-suitable K340 powder from recycled scrap, meeting the requirements for DED applications while providing substantial environmental benefits.