Strengthening 316L austenitic steel through a bimodal approach with ODS steel

Abstract Achieving a balance between strength and ductility has long been a challenge in materials science. Strategies such as bimodal grain size distribution have been proposed to overcome this limitation by combining coarse grains for ductility with fine grains for strength. This study presents a novel approach to preparing bimodal 316L austenitic stainless steel, integrating fine-grained oxide dispersion-strengthened (ODS) steel as the strengthening matrix with coarse-grained austenite steel. The fine-grained ODS phase, prepared by mechanical alloying, provides uniform microstructural properties and controls the overall alloy structure. The tensile properties of the bimodal structures were analysed, revealing that a volume fraction of 70–80% fine grains achieves optimal strength–ductility synergy, deviating from the conventional Hall–Petch relationship. This innovative use of ODS steel demonstrates its potential to enhance mechanical performance and scalability, offering a versatile tool for tailoring advanced austenitic steels. Graphical Abstract