Effect of Aging Temperature and Time on Secondary Phase Precipitation and Texture in an Ultrafine Grained 2205 Duplex Stainless Steel after Cold Rolling

Abstract The present work evaluates the precipitation of secondary phases in a cold-rolled ultrafine-grained 2205 duplex stainless steel after aging at temperatures ranging from 600°C to 950°C for different annealing times (300–86,400 s). X-ray diffraction, scanning electron microscopy coupled with electron backscattered diffraction, and transmission electron microscopy were used for microstructural characterization. Mechanical properties were evaluated using tensile and Vickers microhardness tests. σ- (sigma), χ- (chi), and chromium carbide (M23C6) phases were identified. σ- and austenite phase volume fractions increased with aging time, whereas χ-phase and carbides remained nearly constant, and the ferritic volume fraction decreased. Inverse pole figures of σ-phase, for a specimen aged at 850°C for 24 h, showed a localized distribution of orientations, normal to the rolling direction, being centered around the [001], whereas for the other annealing conditions, a concentration between the orientations [001] and [110] was observed. Although mechanical strength was increased, the ductility was reduced as the secondary phase precipitation proceeded.