Tailoring the Mechanical Properties Through the Control of Heat Treatments in a Precipitation Hardening Metastable Stainless Steel

This research focusses on a complex precipitation (Ni3(Ti,Al)) hardenable metastable stainless steel. Dual phase (austenite, γ/martensite, α′) and ultrafine grained austenitic microstructures obtained after applying isochronal heat treatments (0.1–10 ℃/s) to a cold-rolled (CR) metastable stainless steel have been microstructurally and mechanically characterized using different experimental techniques (optical microscopy, SEM, TEM, magnetic measurements, tensile tests). A wide range of strength (2.1–1.1 GPa) and elongation (3–25%) values have been obtained using sub-size samples (7 mm in gauge length). The scientific aim is the understanding of those microstructural parameters and mechanisms that influence the achievement of ultra-fine grained microstructures and control or the mechanical behaviour of different complex microstructures in this type of steels. Whereas the industrial aim would be to expand the applicability of this steel and use this scientific knowledge to design steels with optimized microstructures and mechanical properties.