材料期刊网

为了消除铸造316L不锈钢铸态组织的枝晶偏析,采用箱式电阻炉对该材料进行了均匀化退火处理的研究.并利用能谱仪、直读光谱仪测试和扫描电镜、光学显微镜观察等方法,研究了该材料铸态组织及枝晶间和枝晶内化学成分的特点,发现了不同的均匀化退火工艺对该材料显微组织的影响规律.并以空位扩散机制为基础,进行了均匀化动力学分析,建立316L合金的均匀化扩散方程.结果表明,铸造316L不锈钢铸态组织存在严重枝晶偏析,枝晶间的Cr、Mo、Ni、Mn等合金元素含量比枝晶内的高.在均匀化过程中,随着退火温度的上升、时间的增长,组织中高熔点共晶相逐渐溶解,均匀化效果增强.当均匀化退火工艺为1150℃×20 h的固溶处理时,铸造枝晶偏析90％消除,可以得到均匀的奥氏体组织.这与均匀化动力学分析结果基本一致.

In order to eliminate the dendrite segregation microstructure,the homogenization annealing treatment of cast 316L stainless steel by box type resistance furnace was carried out.The characteristics of the as-cast microstructure and the chemical composition in and between dendrite were studied by means of energy dispersive spectrometer(EDS) analysis,direct reading spectrometer,scanning electron microscopy(SEM) and optical microscope,the influence of different annealing processes on the microstructure of the steel was found.Based on the vacancy diffusion mechanism,the diffusion kinetics and kinetic equations during the homogenizing heat treatment were investigated,and the uniform diffusion equation of the 316L steel was established.The results show that as cast microstructure of the cast 316L stainless steel presents serious dendritc segregation,and the content of alloy element between dendritic crystal is higher than in dendritic crystal.During the homogenizing heat treatment,with the increasing of the annealing temperature and the growth of time,the high melting eutectic phase gradually dissolves,and the effect of homogenization is enhanced.When homogenizing annealing at 1150 ℃ for 20 h,90％ of casting dendrite segregation will be eliminated,and uniform austenite structure can be obtained.There is a good agreement between the experiment results and the calculated one.