S32760超级双相不锈钢中σ相的析出规律  

Precipitation behavior of σ phase in UNS S32760 super duplex stainless steel

作　　者：罗照银 李静媛[1] 

机构地区：[1]北京科技大学材料科学与工程学院,北京100083

出　　处：《材料热处理学报》2015年第4期110-115,共6页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51174026);十二五国家科技支撑计划(2012BAE04B02)

摘　　要：利用光学显微镜、纳米力学探针、扫描电镜、能谱仪和透射电镜等方法,研究了S32760超级双相不锈钢热轧板材经1100℃固溶60 min,并在760~1040℃保温30 min过程中σ相的析出规律,分析了W元素对σ相析出行为的影响。结果表明,σ相中富集大量Cr、Mo和W元素,贫Ni且不含N。W提高了σ相在高温区间的稳定性,使σ相在760~1020℃的范围内均能析出。在析出鼻尖温度880℃时效30 min后,钢板硬度达最大值37.1 HRC,α相体积分数降至5.3%。随着时效温度的升高,σ相的形貌变化规律为:粒状→粒状+短棒状→片层状→块状。在鼻尖温度(880℃)附近,σ相和γ2相以片层共析形貌析出,而在高温阶段(如960℃)则呈现出γ2相被大块σ相包围的形貌。Precipitation behavior of σ phase in UNS S32760 super duplex stainless steel sheet after solution treating at 1100 ℃ for 60 min and followed by aging treatment at temperature from 760 ℃ to 1040 ℃ for 30 min was investigated by means of optical microscopy( OM),nano-indentation tests,scanning electron microscopy( SEM),energy dispersive spectrometer( EDS) analysis and transmission electron microscopy( TEM). The effect of W on the precipitation behavior was analyzed. The results show that σ phase is rich in Cr,Mo,W,poor in Ni and no N element contained. The stability of σ phase can be improved by W,leading to σ phase precipitation in a wide range from760 ℃ to 1020 ℃. The hardness of the sheet reaches its maximum value of 37. 1 HRC and the ferrite volume fraction decreases to 5. 3%after aging at the nose temperature of 880 ℃ for 30 min. With aging temperature increasing,the morphology of σ phase changes from granular to granular and short bar,further to eutectoid structure and finally block. Eutectoid σ phase and γ2phase are precipitated near the nose temperature( 880 ℃),while the morphology of γ2phase surrounded by σ phase appears at higher aging temperature( 960 ℃).

关 键 词：S32760超级双相不锈钢 时效 Σ相 二次奥氏体γ2 相变 

分 类 号：TG142.71[一般工业技术—材料科学与工程]