00Cr12NiNbTi不锈钢热轧中析出行为

Precipitation behavior of 00Cr12NiNbTi stainless steel during hot rolling

对00Cr12N iNbTi铁素体不锈钢进行加热、粗轧、精轧及卷取过程的模拟实验,应用扫描电镜、透射电镜、化学相分析及热模拟等方法对试样中析出物进行了定性定量分析。结果表明:加热到1140℃,保温0、45和90 m in后,粒子主要为TiN,Ti的固溶率为66.3%,N的固溶率为1.3%;从粗轧到精轧,微米级的小颗粒减少,大颗粒增多,颗粒平均尺寸由1.8μm增大到3.2μm,有聚集长大现象;在热轧过程中微米级粒子形貌为方形或球形,基本保持稳定;纳米级的(Nb,Ti)C颗粒在精轧阶段开始析出,卷取保温及缓冷至室温过程中大量析出,多分布于晶界及晶内处,在较高温度下卷取会析出较多的纳米级(Nb,Ti)C颗粒。

Simulation experiments including reheating,rough rolling,finishing and coiling were conducted on 00Cr12NiNbTi ferritic stainless steel.The precipitates in the steel were examined by means of scanning electron microscopy,transmission electron microscopy,chemical phase analysis and thermo-mechanical simulation.The results show that the main precipitates are TiN in the steel heated at 1140 ℃ for 0 min,45 min and 90 min.The solid solution rate of Ti is 66.3 percent and N is 1.3 percent for the steel heated at 1140 ℃.From rough rolling to finishing,the average size of the precipitates increases from 1.8 μm to 3.2 μm with aggregation growing of the micro-scale particles by dissolution of the small precipitates and growth of the big precipitates.The nano-scale precipitates with spherical and square shape keep stable primarily in the process of hot rolling temperature.The precipitation of（Nb,Ti）C nano-carbides begins in the finishing stage and mainly occurs during the coiling,holding and slow cooling.（Nb,Ti）C carbides are mainly distributed in grains and at grain boundaries and the higher the coiling temperature is,the more of nano-scale（Nb,Ti）C particles is precipitated.