The effects of ferrite proportion and precipitates on the dual-phase corrosion properties of S32750 super duplex stainless steel are investigated with different annealing temperatures. When the specimens are annealed at 900 and 950 °C, respectively, the dual-phase microstructure changes due to the precipitation of σ phase. Meanwhile, the passivation behavior of the specimens weakens, and the pitting corrosion potential decreases. With the increase in annealing temperature, especially over 1150 °C, the ferrite content and the grain size increase significantly and the pitting resistance equivalent of the ferrite phase decreases. The optimal annealing temperature of the tested steel is 1050–1100 °C. Under this condition, the dual-phase proportion is close to 1:1, no obvious secondary phase precipitates in the matrix, and both the ferrite and the austenite phases present excellent corrosion resistances.

中文翻译：

---

不同退火温度下铁素体比例和沉淀对S32750超级双相不锈钢双相腐蚀的影响

研究了不同退火温度下铁素体比例和析出物对S32750超级双相不锈钢双相腐蚀性能的影响。当试样分别在 900 和 950 °C 退火时，由于 σ 相的析出，双相组织发生了变化。同时，试样的钝化行为减弱，点蚀电位降低。随着退火温度的升高，特别是超过1150℃，铁素体含量和晶粒尺寸显着增加，铁素体相的抗点蚀当量降低。试验钢的最佳退火温度为 1050-1100℃。在此条件下，双相比例接近1:1，基体中没有明显的第二相析出，