On the influence of microstructure on the fracture behaviour of hot extruded ferritic ODS steels

•High interfacial particle-matrix strength and small size of sub-micron particles predominantly enhances fracture toughness.•Crack blunting due to elongated coarse grains contributes predominantly towards improving fracture toughness.•Crystallographic texture and sub-micron particle alignment do not play a major role in fracture toughness anisotropy.•Higher flow stress is not the predominant reason for higher fracture toughness.