Machining swarf constitutes a major source of material loss in metal processing, yet its recyclability is constrained by oxidation and contamination. Near-solidus forging (NSF) provides a solid-state consolidation route operating close to the alloy solidus temperature, where it is suggested that (although not verified) localised liquid formation enables densification under comparatively low loads. This study examines the applicability of NSF to EN24 steel swarf in its industrially generated, uncleaned condition. Swarf was pre-compacted into briquettes, de-oiled thermally, and consolidated before being forged under NSF conditions at 1350 °C. The forged billet exhibited a predominantly martensitic microstructure with a measured porosity of ∼1.5 %. Hardness mapping yielded bulk values of ∼400 HV, while tensile testing demonstrated yield and ultimate strengths of ∼1000 MPa and ∼1080 MPa respectively, exceeding the corresponding EN24T-V literature data. Reduced ductility, however, was attributed to incomplete tempering, residual porosity, and/or localised soft regions associated with feedstock contamination. These findings demonstrate that whilst currently not optimised, NSF can convert heterogeneous steel swarf into mechanically robust, consolidated billets, indicating its potential as an energy-efficient, closed-loop recycling pathway for metallic alloys.
Slater et al. (Fri,) studied this question.