超纯铁素体不锈钢热变形过程中的析出行为

利用热力模拟实验机及试验轧机研究了添加Ti,V的超纯中铬铁素体不锈钢热变形过程中的析出行为变化特点,并采用热动力学计算及透射电子显微镜观察来表征析出相特征.结果表明:热变形过程中形成的析出相主要为TiC,这与热动力学分析一致.这些析出相的特征与变形温度密切相关,随着变形温度的降低,析出相TiC尺寸更加细小且分布更加弥散.这主要是由于变形温度降低时扩散速率相对较低,不利于析出相长大,而晶体缺陷增加,形变诱导析出的有效形核位置增加.这一热变形过程中的析出行为变化规律在中试试验条件下得到了验证.

Precipitation Behavior of Ultra-pure Ferritic Stainless Steel During Hot Deformation

The precipitation behavior of an ultra-pure medium-chromium ferritic stainless steel with addition of Ti and V during hot deformation was studied using a thermomechanical simulator and pilot rolling mill. The characteristic of precipitates was investigated using thermodynamic calculation and transmission electron microscopy. The results showed that TiC is primary precipitate formed during hot deformation， in agreement with the thermodynamic calculation. The characteristic of these precipitates is closely dependent on deformation temperature. The TiC formed during hot deformation at relatively low temperature is finer in size and denser in dispersion than that at high temperature. This can be explained by a combination of the slower diffusion rate associated with the lower deformation temperature which is unfavorable to precipitate growth， and increasing lattice defects due to lower deformation temperature which can generate more nucleation sites for the strain-induced precipitates. This precipitation behavior during hot deformation is confirmed by the pilot rolling experiments.