Abstract: Taking medium carbon steel 42CrMo as test steel, through established solidification heat transfer model of 300 mm x400 mm continuous casting bloom? in reasonable reduction zone the reduction of No. 4,5 ,6 and 7 roller being "1 mm-2 mm-3 mm-1 mm” is defined, and the industrial experiment is carried out. The experimental results show that the soft reduction process has little effect on the solidification structure of the bloom, but the central compactness and segregation can be improved obviously. The size of the largest porosity point in the core of bloom is reduced from 1 106 μm x 608μm to 600 μm x 334 μm; the carbon segregation index range on the cross section is reduced from 0. 889 ~ 1. 095 to 0. 962 ~ 1. 064. The soft reduction process can effectively improve the internal quality of the bloom.

摘要： 以中碳钢42CrMo为试验钢,通过建立300 mm×400 mm连铸大方坯凝固传热模型,确定合理压下区间4^#～7^#辊压下量分别为"1 mm-2 mm-3 mm-1 mm",并进行工业试验。试验结果表明,轻压下工艺对铸坯凝固各组织占比影响不大,但可明显改善中心致密性和偏析。铸坯芯部最大疏松点尺寸由1 106μm×608μm缩小至600μm×334μm,横截面上碳偏析指数范围由0.889～1.095缩小至0.962～1.064。轻压下工艺可有效改善铸坯内部质量。

关键词: 42CrMo钢, 轻压下, 大方坯, 凝固组织, 中心偏析