304不锈钢中“晶粒团簇”显微组织的特征与晶界特征分布的关系

The relationship of grain-cluster microstructure and grain boundary characteristic distribution in 304 stainless steel

采用电子背散射衍射(EBSD)及取向成像显微(OIM)技术研究了冷轧变形量对再结晶后304不锈钢显微组织及晶界特征分布(GBCD)的影响。结果表明,经过冷轧变形5%及高温(1100℃)短时间(5 min)再结晶退火可将304不锈钢的低ΣCSL(Σ≤29)晶界比例提高到75%(Palumbo-Aust标准)以上,并形成了大尺寸"互有Σ3n取向关系晶粒的团簇"。这是提高低ΣCSL晶界比例后显微组织的重要特征。对晶粒团簇中的晶粒进行孪晶链及取向孪晶链的分析,可以确定晶粒团簇内任何两个晶粒之间的多重孪晶阶次。在一个被分析的团簇内,观察到两个晶粒之间最高为Σ38取向关系。随着再结晶退火前冷轧变形量的增加,晶粒团簇的尺寸减小,同时低ΣCSL晶界的比例也下降。

The effect of thermal-mechanical processing on microstructure and grain boundary characteristic distribution（GBCD） of 304 stainless steel was studied by means of electron back-scatter diffraction（EBSD） and orientation imaging microscopy（OIM） technique.The proportion of low Σ（Σ≤29） coincidence site lattice（CSL） grain boundaries was increased to 75% by slight cold rolling and annealing at（1 100 ℃） for short time.The large grain-cluster,in which all the grains have Σ3~n（n=1,2,3…） mutual misorientation,is the key microstructure affecting the GBCD.Twin chain of grains and orientations in a grain-cluster were analyzed,by which means the order of multiple twins between any grains pair could be identified,and the twin relationships up to 8th generation（Σ3^8） were found in this grain-cluster.The mean size of the grain-cluster and proportion of low Σ CSL boundaries decreased with the increasing of pre-strain.