Preprint of "In-Situ Yttria Formation via Powder Metallurgy as an Approach to Strengthened and Corrosion-Resistant AISI 316L ODS Steels"

General description: The preprint for a publication, "In-Situ Yttria Formation via Powder Metallurgy as an Approach to Strengthened and Corrosion-Resistant AISI 316L ODS Steels", being submitted for review. Abstract: The development of oxide dispersion strengthened (ODS) austenitic steels is critical for high-temperature structural applications, yet balancing mechanical strengthening and corrosion resistance remains a challenge in powder metallurgy processing. This study investigates the in-situ formation of yttria-based dispersoids in AISI 316L ODS steels modified with titanium, using yttrium hydride (YH2) as a precursor. Mechanical alloying (MA) durations of 1, 4, and 8 hours were evaluated to optimise the trade-off between chemical homogeneity and carbon contamination. Results indicate that a 4hour milling window is optimal, achieving a uniform distribution of alloying elements while maintaining carbon content below the threshold for deleterious carbide network formation. Consolidation via spark plasma sintering (SPS) at 1100 °C triggered complete phase reversion to an austenitic matrix and in-situ precipitation of ultra-fine Y2O3 and Y2Ti2O7 nanoclusters. These dispersoids provided significant thermal stability, maintaining grain size below 1 µm. Mechanical testing revealed a remarkable step change in properties: the ODS variants achieved room-temperature yield strengths of 1092–1172 MPa, a nearly fourfold increase over conventional 316L. Critically, these alloys retained approximately 80% of their strength at 600 °C. Electrochemical evaluation via double-loop electrochemical potentiokinetic reactivation (DL-EPR) and potentiodynamic polarisation in simulated seawater demonstrated that, despite the incidental carbon pickup, the ODS alloys exhibited 0% sensitisation (DOS) and a breakdown potential (Eb) of 500 mV, comparable to wrought 316L.The ODS modification introduced a unique repassivation capability (Erp > 0 mV), attributed to the yttrium cations. This work demonstrates that optimised in-situ ODS processing not only triples the mechanical performance of 316L but also ensures full electrochemical integrity in aggressive chloride environments. Versions: V1 - an original version that has been submitted to Materials Degradation on 2026-08-25. Files