采用光学显微镜、扫描电镜和能谱仪考察了时效处理时间对固溶态与轧制态UNS S32304不锈钢组织和耐晶间腐蚀性能的影响;通过双循环动电位再活化试验和草酸腐蚀试验分别评估了经不同时间时效处理后,不同状态试样的晶间腐蚀敏感性。结果表明:时效0.5 h时固溶态试样未发现二次相,轧制态试样有二次奥氏体在铁素体内优先析出;时效4 h,固溶态试样相界处析出圆粒状M₂₃C₆和小颗粒状二次奥氏体,而轧制态试样只有锯齿状二次奥氏体沿相界析出。继续延长时效时间,两种试样的锯齿状二次奥氏体皆变得宽大且向铁素体内延伸,且时效处理时间相同时,轧制态试样中二次相的析出数量比固溶态的多;此外,延长时间还会使得固溶态和轧制态试样的晶间腐蚀敏化系数增大,且后者的敏化系数比前者大,耐蚀性不如前者。

The effect of aging treatment time on the microstructure and intergranular corrosion resistance of UNS S32304 stainless steel with solid solution state and rolled state was investigated by optical microscopy, scanning electron microscopy and energy spectrometer. The sensitivity of intergranular corrosion of samples with different states after aging treatment for different time was evaluated by double-cycle potentiodynamic reactivation test and oxalic acid corrosion test. The results showed that no secondary phase was found in the solid solution sample after aging for 0.5 h, and secondary austenite was preferentially precipitated in ferrite in the rolled sample. After aging for 4 h, the spherical M₂₃C₆ and small granular secondary austenite precipitated at the phase boundary of the solid solution sample, while only serrated secondary austenite precipitated along the phase boundary of the rolled sample. With the aging time prolonging, the serrated secondary austenite of the two samples became wide and extended into ferrite, and when the aging treatment time was the same, the precipitation amount of the secondary phase in the rolled sample was more than that in the solid solution sample. In addition, prolonging the time would also increased the sensitization coefficient of intergranular corrosion of samples with solid solution state and rolling state, the latter's sensitization coefficient was larger than the former, and its corrosion resistance was not as good as the former.