Phase-Specific Precipitation of Intermetallic Phases in Fe Al Mn Ni C Duplex Steels

Abstract

A Fe–Al–Mn–Ni–C steel is designed explicitly to precipitate intermetallic phases in specific phases of a duplex steel. CALPHAD-assisted alloy design is carried out with respect to an innovative “solublility-assisted precipitation” (SAP) mechanism. A four phase equilibrium comprising of ferrite, austenite, κ-phase (Fe3AlC), and B2-phase (NiAl) is stabilized in a suitable annealing window. The processing conditions are adjusted according to elemental partitioning and consequential stabilization of κ-phase in austenite and B2-phase in ferrite. The feasibility of the SAP mechanism is validated by investigation of microstructure and precipitation evolution using electron microscopy and site-specific atom probe tomography.