不同热处理状态下2205双相不锈钢中析出相变化的讨论

双相不锈钢因热处理或焊接过程，在300～1100 ℃影响区域内析出σ相,χ相等金属间相以及Cr2N,M23C6等析出相，这种析出倾向既受温度范围、冷却速度等因素的影响，又受合金元素含量的影响。本研究的目的是考察2205双相不锈钢不同热处理状态下析出相的变化。在选择好合适的电解制度后，实验利用电解分离的方法将不同时效条件下的析出相从基体中分离出来。通过扫描电镜（SEM）和X射线衍射（XRD）定性分析了析出相的形貌和结构特性，并利用激光粒度仪（DLS-sizer）分析提取残渣的粒度分布。此外，利用氧氮仪和碳硫仪分析了不同时效条件下析出相中氮和碳的含量，同时用化学湿法和电感耦合等离子光谱仪对析出相的分离与定量成分检测进行研究。实验用化学和物理的手段揭示了双相不锈钢在不同热处理状态下析出相种类、含量、元素组成和颗粒粒度的变化。

Discussion on transformation of precipitate phases in 2205 duplex stainless steel with different isothermal treatment situation

Due to isothermal heat treatment or welding, duplex stainless undergoes a variety of decomposition processes at a temperature ranging from 300-1100 ℃, which could form inter-metallic phases like σ phase and χ phase, as well as preciptiate phase Cr2N and M23C6, etc. These processes not only are influenced by temperature and cooling speed, but also are affected by alloy element content. The purpose of the research was to work out the qualitative and quantitative analysis of precipitate phases in 2205 duplex stainless steel with different isothermal heat treatment situation. After choosing the electrolyte and electrolytic systems, we use electrochemical method to extract precipitate phases from the matrix. Scanning electron microscope (SEM) and X-ray diffraction (XRD) were used to examine their modality and structure. Particle size distribution was performed by dynamic laser scattering sizer (DLS-Sizer). Furthermore, oxygen-nitrogen analyzer and carbon-sulfur analyzer were applied to measure the content of nitrogen and carbon in precipitate phases. Separation and quantitative analysis of precipitate phases were carried out by wet chemical analysis and inductively coupled plasma spectrometry. In a word, combining chemical and physical methods, our research reveals the transformation of precipitate phases, species, content, elemental composition and particle size distribution during different isothermal heat treatment situation.