预处理状态对轧制退火后奥氏体不锈钢晶界特征分布的影响
Effect of Pre-treatment on Grain Boundary Characteristic Distribution of Cold-rolled and Annealed Austenitic Stainless Steel
方晓英, 蔡正旭, 王卫国
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作者单位：(山东理工大学 机械工程学院材料系, 山东 淄博 255049)
中文关键字：晶界特征分布； 轧制退火； 奥氏体不锈钢； EBSD
英文关键字：grain boundary characteristic distribution; cold-rolling and annealing; austenitic stainless steel; EBSD
中文摘要：采用电子背散射技术研究了不同预处理状态的304奥氏体不锈钢经小压下(6%)冷轧和高温(1050 ℃)短时(5 min)退火后的晶界特征分布。结果表明，预先在1050 ℃下固溶30 min的合金样品经冷轧退火后其低Σ重位点阵晶界比例最高，达70%以上，较固溶状态提高了近20%，而且由互成 Σ3n(n＝0，1，2，3…)界面关系的晶粒团簇的尺寸明显增加，为晶粒平均尺寸的10～15倍。而未经固溶和固溶后在650 ℃下时效2 h的合金样品在后续的轧制退火过程中低Σ重位点阵晶界比例均有所下降，仅为40%～50%，而且 Σ3n晶粒团簇尺寸为晶粒平均尺寸的2～5倍。分析认为，后两者未能实现晶界特征分布优化主要是由于碳化物的存在阻碍了晶界的迁移，尤其是非共格Σ3晶界和某些一般大角度晶界的广泛迁移所致。
英文摘要：The grain boundary characteristic distributions (GBCDs) of cold rolled (with 6% thickness reduction) and annealed (at 1050 ℃ for 5 min) 304 austenitic stainless steel pre-treated via three different means were investigated by electron-back scatter diffraction (EBSD) techniques. The results show that the highest fractions (>70%) of low Σ coincidence site lattice (CSL) boundaries is achieved in the specimen which is cold-rolled and annealed after solid solution treatment at 1050 ℃ for 30 min, which is increased nearly by 20%. The size of Σ3n grains cluster increases significantly and is about 10～15 times of the average grain size. However, the fractions of low Σ coincidence site lattice (CSL) boundaries decrease in the other two cold-rolled and annealed specimens, one of which is not previously solid solution heat treated and the other is pre-aged at 650 ℃ for 2 h after solid solution heat treatment. It is only 40%～50% and the size of Σ3n grains cluster is 2～5 times of the average grain size. Further analysis points out that the presence of carbide plays a negative role in GBCD optimization via impeding the extensive migration of grain boundaries, particularly incoherent Σ3 boundaries and some random high angle grain boundaries.