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对高温固溶之后的SAF2906双相不锈钢进行时效处理,固溶温度为1200℃,保温时间1h,时效温度为650℃、700℃、750℃、800℃、850℃、900℃和950℃,采用扫描电镜(SEM)、X射线衍射(XRD)以及透射电镜(TEM)等方法观察SAF2906双相不锈钢中析出相的形态,用EDS能谱测量析出相中各化学元素的含量,通过恒温拉伸机对试样进行恒温拉伸,分析在不同实验温度下试样伸长率的变化。实验结果表明,在本实验条件下,σ相的析出量随时效温度的升高呈现先增大后减小的趋势,在850℃左右达到最大,SAF2906双相不锈钢中的σ析出相分布规律与同类型双相不锈钢有相似之处,形核位置大部分在α-铁素体内部和γ-奥氏体/α-铁素体两相之间,部分析出相出现在γ-奥氏体内部;σ相在超塑拉伸过程变形后期容易导致断裂,在变形温度为850℃与900℃时,试样伸长率分别可以达到382%和538%,当温度为950℃时,随着保温时间的延长,σ相在试样中的比例不断下降,同时试样伸长率不断上升,当保温时间长于5min,σ相比例下降到5%以下,此时伸长率可达1000%。
SAF2906 duplex stainless steel after solution heat treatment was aged at 1200 ℃, holding time 1h, aging temperature 650 ℃, 700 ℃, 750 ℃, 800 ℃, 850 ℃, 900 ℃ and 950 ℃ The morphology of precipitates in SAF2906 duplex stainless steel was observed by scanning electron microscopy (SEM), X-ray diffraction (XRD) and transmission electron microscopy (TEM). The content of each chemical element in precipitated phase was measured by EDS spectroscopy. The specimens were heated at constant temperature, and the changes of the elongation of the specimens at different experimental temperatures were analyzed. The experimental results show that under the experimental conditions, the precipitation of σ phase increases first and then decreases with the increase of aging temperature and reaches the maximum at about 850 ℃. The distribution of σ precipitation phase in SAF2906 duplex stainless steel The same type of duplex stainless steel have similarities, most of the nucleation sites in the α-ferrite and γ-austenite / α-ferrite between the two phases, precipitated phase appeared in γ-austenite Internal; σ phase easily lead to fracture in the late stage of the deformation of the superplastic process, at the deformation temperature of 850 ℃ and 900 ℃, the sample elongation can reach 382% and 538%, respectively, when the temperature is 950 ℃, with the As the holding time prolongs, the proportion of σ phase in the sample decreases continuously and the elongation of the sample increases continuously. When the holding time is longer than 5 min and the σ phase ratio drops below 5%, the elongation can reach 1000%.