形变热处理对316L奥氏体不锈钢晶界特征分布的影响

Effect of thermo-mechanical processing on grain boundary character distribution of 316L austenitic stainless steel

采用5%的单向压缩与1000℃退火的形变热处理工艺,对316L奥氏体不锈钢的晶界特征分布进行了优化,并且通过定位观察的方法研究了晶界特征分布优化的机理。结果表明,随着退火时间的增加,特殊晶界比例逐渐增加;当退火时间达到90 min时,试样的特殊晶界比例最高(69.5%),并且得到了打断的大角度随机晶界网络。晶界特征分布优化的机理是,小变形试样在退火过程中发生了局部再结晶,首先产生了以特殊晶界等低能量晶界为主的小晶粒群;之后小晶粒群中能量较高的大角度晶界开始迁移并消失,最终材料的特殊晶界比例得到了提高。

Optimization of grain boundary character distribution（ GBCD） was carried out on 316 L austenitic stainless steel with thermomechanical processing（ TMP）,which was performed by 5% unidirectional compression and subsequent annealing at 1000 ℃. In addition,the mechanism was investigated by localization observation. The results show that the fraction of low-Σ boundaries increases with the increase of annealing time. The highest fraction of low-Σ boundaries（ about 69. 5%） associating with interrupted network of large angle grain random boundaries is obtained when the annealing time is 90 min. The mechanism of GBCD is investigated that the local recrystallization occurs in the small deformation specimen during the annealing process. The low energy boundaries such as low-Σ boundaries are nucleated during the recrystallization of small grains group. And then the high energy boundaries such as large angle grain random boundaries migrates and disappears. It leads to the increase fraction of special boundaries.