Microstructure and Tensile Properties of Annealed Low‐Density Duplex Steel

A novel Fe‐18.17Mn‐10.51Al‐1.04C‐5.88Ni duplex steel composition is designed for reduced density and enhanced strength. The alloy is vacuum induction melted, cast into a plate in a copper mold, hot rolled, water quenched, and cold rolled for 80% reduction in thickness (PD1‐CR). The deformed material contains 57.3 and 42.7% austenite and ferrite, respectively. Ferrite depicted higher dislocation density, microstrain, with deformed texture components of cube and rotated Goss. Austenite showed A‐type and rotated copper texture components. The deformed duplex steel is annealed at 930 °C for 5 (PD1‐CA5) and 15 min (PD1‐CA15). With annealing time, an increased amount of austenite is recrystallised with the signature of enhanced intensity of Goss/Brass texture component, higher fraction of high‐angle grain boundary, and enhanced misorientation angle. Continued annealing, delta ferrite is recovered with an increased low‐angle grain boundary fraction. Part of the delta ferrite transformed into austenite and got ordered to B2. Higher yield strength (1430 MPa) of PD1‐CA5 than that of PD1‐CA15 is mainly due to the increased contribution from higher residual dislocation density. PD1‐CA15 displayed enhanced ductility because of partial recrystallisation of austenite, but precipitation of B2 increased strain hardening.