国内外2205双相钢连铸坯凝固组织及碳偏析分析

以国内外两家先进不锈钢生产企业的2205双相不锈钢连铸方坯为研究对象,对比分析了其相应的凝固组织特征和宏观碳偏析分布。研究发现,国外2205连铸坯凝固组织柱状晶较为发达,柱状晶比例为76%,宏观碳偏析总体较低;而国内2205连铸坯等轴晶占主要部分,等轴晶比例为58%,存在严重的中心碳偏析。通过进一步对比国外样品柱状晶区和等轴晶区的致密度得出,柱状晶区平均致密度为0.89,高于等轴晶的0.84,高致密度的凝固组织对降低宏观偏析有利。因此,为了获得较为均匀的连铸坯成分和较低的宏观偏析度,合理的柱状晶和等轴晶比例非常重要。

Analysis of solidification structure and carbon segregation of 2205 duplex steel continuous casting billets at home and abroad

The 2205 duplex stainless steel continuous casting billets of two advanced stainless steel production enterprises at home and abroad were taken as the research object, and the corresponding solidification structure characteristics and carbon macrosegregation distribution were compared and analyzed. The study found that the columnar crystals in the solidified structure of 2205 continuous casting slabs abroad were more developed, the proportion of columnar crystals was 76%, and the overall carbon macrosegregation was low. The equiaxed crystals of domestic 2205 continuous casting billet accounted for the main part. The proportion of equiaxed crystals was 58%, and there was serious central carbon segregation. Furthermore, the density of the columnar crystal area and the equiaxed crystal area of the foreign samples was compared. The average density of the columnar crystal area was 0.89, which was higher than 0.84 of the equiaxed crystals. Therefore, in order to obtain a more uniform composition of the continuous casting slab and a lower degree of macrosegregation, a reasonable ratio of columnar crystals to equiaxed crystals was very important.