An Innovative Large-Scale Preparation Method for ODS Steel: Zone Melting with Built-In Precursor Powder

Abstract

To develop a melting-based larger-scale fabrication process for oxide dispersion strengthened (ODS) steel, this study proposed a method of zone melting with built-in precursor powder (ZMPP), followed by hot forging and aging treatments. A 50 kg ingot was successfully prepared, highlighting the scalability of this innovative process. Microstructural analysis revealed a predominantly lath martensite matrix with a small amount of ferrite in the hot-forged ODS steel, without oxide particle aggregation. Aging at 750 °C resulted in the formation of sub-micron-sized Cr₂₃C₆ particles at grain boundaries and martensitic lath interfaces, accompanied by a high-density (7.64 × 10²³ m⁻³) nano-scale (~ 6 nm) Y–Si–O complex oxides after 25 h. Additionally, the hot-forged sample exhibited a high yield strength (871 MPa) but limited ductility (5.0%). Aging treatments led to an increase in ductility but a decrease in yield strength. Notably, prolonged aging maintained the strength level of steels while enhancing ductility, with a 23.3% total elongation observed after 25 h. The novel ZMPP method, preparing high-quality ODS steels with uniform microstructure and good mechanical properties, provided a new avenue for large-scale production of ODS steels.