小形变冷轧304不锈钢高温和低温退火晶界特征分布研究

Study on Grain Boundary Character Distributions in Annealed 304 Stainless Steel Annealed at High Temperature and Low Temperature After Slight Cold-rolling

采用电子背散射衍射(Electron-back scatter diffraction,EBSD)技术对比研究了小形变冷轧(厚度减缩量6%)304不锈钢经低温退火和高温退火后的晶界特征分布。结果表明,相比于轧制前的再结晶状态,轧制变形后的高低温退火处理都在一定程度上提高了合金中低Σ重位点阵(Coincidence site lattice,ΣCSL)晶界的比例,增幅均达20%以上;但在其晶界特征分布(grain boundary character distribution,GBCD)中,互成Σ3n取向关系的晶粒团簇(Cluster of grains with Σ3n relationship,Σ3n CG)大小和其外围一般大角度晶界(random high angle grain boundary,HAB)网络的连接特性却存在明显差异。低温退火样品中Σ3n CG尺寸比高温样品大得多,且其HAB网络连通性被低ΣCSL晶界阻断的效果也明显优于高温退火样品。进一步对两个样品的织构和残余亚结构进行对比分析后认为,形变诱发晶界的优先迁移是低温退火样品中获得较大尺寸Σ3n CG和HAB网络连通性被低ΣCSL晶界有效阻断的重要原因。

The grain boundary character distributions in 304 stainless steel was studied in two slightly cold-rolled samples with the thickness reduction of 6% annealed at low temperature and high temperature,respectively.The results show both low temperature and high temperature annealing treatments after cold rolling substantially enhance the fraction of low coincidence site lattice（ΣCSL） grain boundary,which increases as much as 20% compared with the recrystallized sample prior to cold-rolling.However,there is a discrepancy in the size of cluster of grains interfaced by Σ3n relationship（Σ3n CG） and the connectivity of the random high angle grain boundary（HAB） network across the exterior of Σ3n CG in these two samples.For low temperature annealed sample,the Σ3n CG is much larger and the connectivity of HAB network is disrupted by low ΣCSL grain boundaries more effectively.Further grain orientation texture and residual sub-microstructure analysis indicate that strain induces preferential migration of particular grain boundary might be the primary explanation for obtaining large-sized Σ3n CG and effective disruption of HAB network connectivity in low temperature annealed sample.