2205双相不锈钢中σ相的析出行为

Precipitation Behavior of σ Phase in Duplex Stainless Steel 2205

对固溶处理后的双相不锈钢2205进行了不同温度下（750～950℃）的等温时效处理，利用OM观测不同时效条件下析出相的形貌特征，重点观测了800℃下。相的析出过程，并通过EDS，XRD，TEM和电子探针等检测手段对800℃，240min时效处理后试样的内部组织进行了研究，揭示了σ相的析出特征及机理．结果表明：σ相是一种Fe—Cr—Mo金属间化合物，属于四方结构；时效过程中，σ相通过δ铁素体→γ2＋σ反应生成，台金元素Mo的扩散是其形成的主要影响因素；保温240min后，时效温度为800℃时σ相析出量最大，相同时间条件下时效温度为950℃时，σ相析出量明显降低．

The effects of aging conditions on tile morphology features of precipitates of DSS （duplex stainless steel） 2205 after solution treatment were observed by OM, and the precipitation process of σ phase at 800 ℃ were analyzed. In order to investigate the precipitation characteristics and the mechanisms of σ phase, the microstructure of the sample by aging treatment at 800 ℃ for 240 min was studied by EDS, XRD, TEM and EP. The results showed that σ phase which precipitates by the reaction δ→γ2 ＋ σ- is an Fe-Cr-Mo intermetallic compound and the crystal structure is tetragonal, and the diffusion of alloying elements Mo mainly affected its formation. After the same aging time, σ phase precipitates severely at 800 ℃ and slightly at 950 ℃.