Abstract: A micro segregation model of solute elements in the mushy zone in continuously cast bloom of bearing steel GCrl5 is established in consideration of δ/γ phase transformation, which is applied in the solidification heat transfer of 220 mm x 260 mm continuous casting bloom. The results show that accurate solidus and liquidus temperature and relationship between temperature and solid fraction during the solidification process of high carbon steel can been acquired by the model only y phase precipitates out from liquid steel directly during the solidification process of bearing steel GCrl5 ；the segregation ratio of S,P and C is bigger at the final solidification stage, as solid fraction increases, the effect of cooling rate on segregation is more remaritable, the content of S,P and cooling rate have a bigger effect on ZDT. After the continuous casting process parameters optimized based on the solidification heat transfer model, the center carbon segregation ratio is 0.96 to 1. 05 and the internal cracks don't appear.

摘要： 建立了考虑δ/γ相变的GCr15轴承钢大方坯连铸凝固两相区溶质微观偏析模型,并应用于220 mm ×260 mm铸坯的凝固传热。结果表明:通过模型可以获得高碳钢精确的固液相线温度,以及温度与固相率的关系;GCr15轴承钢大方坯凝固过程仅析出γ相,凝固末期S、P和C元素的偏析严重;固相率越大,冷却速率对偏析度的影响更明显;S和P元素含量以及冷却速率对零塑性温度（ZDT）影响较大;采用基于凝固传热模型优化的连铸工艺后,铸坯中心碳偏析指数控制在0.961.05,且铸坯未产生内裂纹。

关键词: GCr15轴承钢大方坯, 微观偏析模型, 溶质元素分配, 高温力学性能, 中心碳偏析