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对S32205双相不锈钢在850℃进行时效处理,采用光镜、扫描电镜、能谱仪、硬度和拉伸测试等手段研究了σ相的析出规律及其对力学性能的影响。结果表明:时效15 min后σ相开始沿γ/α或α/α晶界析出,并向铁素体一侧长大,其析出反应为铁素体发生转变形成σ相和γ2相;时效时间延长,σ相的析出量增加,时效240 min后σ相的含量达到18%,并导致双相不锈钢的硬度明显增加、强度略有提高,而塑性显著下降;拉伸断口的断裂类型由典型的韧性断裂向以准解理断裂为特征的脆性断裂转变。
The aging treatment of S32205 duplex stainless steel at 850 ℃ was studied by using light microscope, scanning electron microscopy, energy dispersive spectroscopy, hardness and tensile test to study the precipitation behavior of σ phase and its effect on the mechanical properties. The results show that the σ phase begins to precipitate along the γ / α or α / α grain boundaries and grows toward the ferrite side after 15 min aging, and the precipitation reaction changes the ferrite to form σ phase and γ2 phase. The aging time , The amount of σ phase precipitated increased, and the content of σ phase reached 18% after 240 min aging, resulting in a significant increase in the hardness of duplex stainless steel with a slight increase in strength and a significant decrease in ductility; the fracture type of tensile fracture was dominated by a typical Transition from ductile fracture to brittle fracture characterized by quasi-cleavage.