薄带连铸Fe-2.7%Si铸带组织和析出物

Microstructure and precipitates in strip-casting Fe-2.7%Si sheet

研究了双辊薄带连铸Fe-2.7%Si合金铸带组织和析出物的形貌特征及分布规律。结果表明,实验钢铸带中间区域具有以表层柱状晶为主、中心细小等轴晶共存的组织,且细小等轴晶区厚度约为600μm,尺寸为10μm^40μm,晶内有大量亚晶。铸带初始织构较为漫散。铸带中的析出物主要为AlN和MnS的复合析出,通常以MnS周边包围AlN的形态存在,析出的位置主要在晶界、亚晶界附近及晶内。表层析出物尺寸为50nm^500nm,中心层尺寸更为粗大,甚至包括1μm以上的特大型析出物。同时,铸带中存在一定的位错,可在一定程度上促进第二相粒子的快速细小析出。

The morphology and distribution of microstructure and precipitates in Fe-2.7%Si alloy strip produced by twin-roll strip casting process were analyzed.The results show that microstructure in the middle of strip is composed of the mixture of main columnar grains at surface layer and fine equiaxed grains at center layer,and the thickness of fine equiaxed grains area with size of10μm^40μm is about 600μm and many sub-grains exist in the fine equiaxed grains.The grains of strip exhibit a random orientation distribution.The main precipitates are the complex of AlN and MnS and usually occur at the vicinity of grain boundary,subgrain boundary and the interior of grain.The sizes of the precipitates at the surface are in the range of 50nm^500nm,while the sizes at the center layer are larger,even including the ones with size over 1μm.Some dislocations are observed in the strip and can promote the rapid precipitation of these fine second phase particles to some extent.