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对2507超级双相不锈钢在920℃进行了不同保温时间的时效处理,采用光学显微镜、扫描电镜、X射线衍射仪和能谱仪分析了不同时效状态下的组织演变规律,通过硬度试验和冲击试验研究了时效时间对2507超级双相不锈钢性能的影响。结果表明,920℃时效处理时,大量的σ相沿γ/α及α/α晶界析出,并向铁素体内部长大,其形成机理为铁素体共析转变成σ相和二次奥氏体γ2;在时效5 min内σ相的析出速率最快,随着时效时间的延长,σ相的含量增加,但析出速率逐渐变小;σ相的出现严重降低了超级双相不锈钢的冲击韧性,并且使其硬度明显增加,冲击功和硬度值的大小与σ相析出量有关,当920℃时效30 min时,σ析出相的含量接近于28%,对应双相不锈钢的冲击功和硬度值分别为6 J和376 HB。
The aging treatment of 2507 super duplex stainless steel at 920 ℃ for different holding time was carried out. The microstructure evolution under different aging conditions was analyzed by optical microscope, scanning electron microscopy, X-ray diffraction and energy dispersive spectroscopy. The hardness and impact test The effect of aging time on the properties of 2507 super duplex stainless steel was studied. The results show that during the aging treatment at 920 ℃, a large amount of σ phase precipitates along γ / α and α / α grain boundaries and grows into the ferrite. The formation mechanism is that ferrite eutectoid transformed into σ phase and secondary austenite Body γ2. The precipitation rate of σ phase was the fastest within 5 min after aging, and the content of σ phase increased with the aging time, but the precipitation rate became smaller gradually. The appearance of σ phase seriously reduced the impact toughness of super duplex stainless steel , And its hardness increased obviously. The values of impact work and hardness are related to the amount of σ phase precipitation. The content of σ precipitation phase is close to 28% at 920 ℃ for 30 min, which corresponds to the impact energy and hardness of duplex stainless steel Respectively 6 J and 376 HB.