薄带连铸AISI304不锈钢中铁素体行为

为了确定薄带连铸AISI304不锈钢凝固过程中残留铁素体的生成及转变行为,采用彩色金相、电解侵蚀、电子背散射衍射分析技术及X射线衍射分析等研究手段对双辊薄带连铸AISI304不锈钢凝固组织及残留铁素体特征进行了研究.结果表明AISI304不锈钢薄带的凝固组织由表层胞状晶区、中间柱状晶区和中心等轴晶区三部分组成.薄带表层胞状晶区内残留铁素体呈棒状,柱状晶区的残留铁素体形态为鱼骨状,中心等轴晶区的残留铁素体呈弯曲的树枝状;薄带的表层胞状晶区残留铁素体的质量分数为4.6%～6.6%,柱状晶区内的残留铁素体质量分数为3.6%～3.7%,中心等轴晶区内的残留铁素体质量分数为11.27%～11.34%;残留铁素体沿着厚度方向呈现"W"状分布. 

Behavior of ferrite in AISI304 stainless steel strips

To determine the formation and transformation behavior of retained ferrite in AISI304 austenitic stainless steel strips during the solidification process, the characteristic of retained ferrite and the solidification microstructure in the steel strips were studied by color metallography, electro-etching, electron backscatter diffraction and X-ray diffraction analysis. In the cast strips, there are three kinds of solidification structures:fine cellular crystals in the surface layer, equiaxed grains in the center, and columnar dendrites between them. The morphology of retained ferrite is rod-like in the fine cellular crystal zone in the surface, comb-like in the columnar dendrite zone, and curved branch in the equiaxed zone in the center. The mass fraction of retained ferrite in the cellular zone, the columnar dendrite zone, and the central equiaxed zone is about 4. 60% to 6. 60%, 3. 60% to 3. 70%, and 11. 27% to 11. 34%, respectively. The residual ferrite shows a W-shaped distribution in the thickness direction.