Analysis ofx Phase Precipitation in Aged 2205 Duplex Stainless Steel

Analysis ofZ phase precipitation in 2205 duplex stainless steel aged at 700 and 750 ~C has been investigated systematically. The experimental results showed that X phase forms prior to the precipitation of δ phase and disappears once tr phase starts to precipitate. This phenomenon indicates that a phase nucleated and consumed the Z phase. The δ phase nucleated mairdy at ferrite/austenite interface and grew inwards into the ferrite phase. The morphology of a phase reveals a coral-like structure at the temperature of 700 ℃ for 120 min followed by quenching in water. The decomposition of ferrite occurs via the following eutectoid reaction： F---＊o＇＋y2. The selected area diffraction pattern of zone axes is[3 1 3-][3 1 3], indicating a characteristic orientation relationship between X phase and δ-ferrite.