| Popis: |
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. |
