工程科学学报.第43卷，第12期：1679-1688.2021年12月 Chinese Journal of Engineering,Vol.43,No.12:1679-1688,December 2021 https://doi.org/10.13374/j.issn2095-9389.2021.09.29.003;http://cje.ustb.edu.cn 压下对重轨钢大方坯内裂纹敏感性的影响 马海涛，张炯明四，尹延斌 北京科技大学治金新技术国家重点实验室，北京100083 ☒通信作者，E-mail:jmz2203@sina.com 摘要为研究压下对连铸坯内部裂纹产生的影响，利用ABAQUS有限元软件建立了230mm×280mm断面大方坯压下数学 模型.通过压下模型对重轨钢连铸坯压下过程进行热力耦合模拟计算，对压下过程中产生的内部裂纹进行了预测.首先，对连 铸坯不同中心固相率为0.3~0.7的温度场进行计算：然后，利用压下模型计算了连铸坯中心固相率0.3~0.7时凝固前沿的等 效塑性应变.研究结果表明，在连铸坯中心固相率为0.3~0.7的位置处分别施加7mm压下量进行压下，连铸坯凝固前沿等 效塑性应变未超过临界等效塑性应变(0.4%)，连铸坯未出现内裂纹：同时，对连铸坯在中心固相率为0.6位置处进行了不同压 下量的研究，研究结果表明.当连铸坯压下量超过7mm时，凝固前沿的等效塑性应变超过临界塑性应变(0.4%)，连铸坯出现 内裂纹，并且压下量越大，连铸坯内裂纹越严重.同时，工业试验结果与模型计算结果基本吻合，验证了模型计算的准确性 关键词大方坯：压下：内裂纹：数值模拟：等效塑性应变 分类号TG142.71 Influence of the soft reduction process on the sensitivity of the inner crack in heavy rail steel bloom MA Hai-tao,ZHANG Jiong-ming.YIN Yan-bin State Key Laboratory of Advanced Metallurgy,University of Science and Technology Beijing.Beijing 100083.China Corresponding author,E-mail:jmz2203@sina.com ABSTRACT Continuous casting technology has greatly improved production efficiency;however,in the continuous casting process of heavy rail steel,problems of center segregation,center porosity,and shrinkage cavity of the bloom occur,which notably affect the billet quality of heavy rail steel.The soft reduction technique can effectively improve these problems,but internal cracks will appear,and the quality of the bloom will deteriorate if the parameters are not properly set.To examine the inner crack induced by the soft reduction of continuous casting bloom,this study established a mathematical model for the soft reduction of a 230 mmx280 mm section bloom by the ABAQUS finite-element software.The thermal-stress coupling model was used to predict the inner crack of the heavy rail steel bloom, using the soft reduction model during the soft reduction process.First,the temperature at different central solidification fractions of 0.3-0.7 in the bloom was calculated.The equivalent plastic strain that was located at the solidification front at different central solidification fractions was then calculated by the soft reduction model.Results indicated that the equivalent plastic strain at the solidification front in the bloom did not exceed the critical strain of 0.%at the central solidification fractions with a reduction amount of 7 mm.Moreover,the inner crack did not occur at the solidification front.Simultaneously,the soft reduction model calculation with a different reduction amount was conducted at the central solidification fraction of 0.6.Results showed that the equivalent plastic strain at the solidification front exceeded the critical plastic strain of 0.4%when the reduction amount was more than 7 mm,which resulted in an inner crack.The greater the reduction amount,the more serious is the inner crack.Concurrently,industrial experimental results had a 收稿日期：2021-09-29 基金项目：国家自然科学基金资助项目(51834002)：中国博士后科学基金资助项目(2021M690371)压下对重轨钢大方坯内裂纹敏感性的影响 马海涛，张炯明苣，尹延斌 北京科技大学冶金新技术国家重点实验室，北京 100083 苣通信作者， E-mail: jmz2203@sina.com 摘    要    为研究压下对连铸坯内部裂纹产生的影响，利用 ABAQUS 有限元软件建立了 230 mm×280 mm 断面大方坯压下数学 模型. 通过压下模型对重轨钢连铸坯压下过程进行热力耦合模拟计算，对压下过程中产生的内部裂纹进行了预测. 首先，对连 铸坯不同中心固相率为 0.3～0.7 的温度场进行计算；然后，利用压下模型计算了连铸坯中心固相率 0.3～0.7 时凝固前沿的等 效塑性应变. 研究结果表明，在连铸坯中心固相率为 0.3～0.7 的位置处分别施加 7 mm 压下量进行压下，连铸坯凝固前沿等 效塑性应变未超过临界等效塑性应变（0.4%），连铸坯未出现内裂纹；同时，对连铸坯在中心固相率为 0.6 位置处进行了不同压 下量的研究，研究结果表明，当连铸坯压下量超过 7 mm 时，凝固前沿的等效塑性应变超过临界塑性应变（0.4%），连铸坯出现 内裂纹，并且压下量越大，连铸坯内裂纹越严重. 同时，工业试验结果与模型计算结果基本吻合，验证了模型计算的准确性. 关键词    大方坯；压下；内裂纹；数值模拟；等效塑性应变 分类号    TG142.71 Influence of the soft reduction process on the sensitivity of the inner crack in heavy rail steel bloom MA Hai-tao，ZHANG Jiong-ming苣 ，YIN Yan-bin State Key Laboratory of Advanced Metallurgy, University of Science and Technology Beijing, Beijing 100083, China 苣 Corresponding author, E-mail: jmz2203@sina.com ABSTRACT    Continuous casting technology has greatly improved production efficiency; however, in the continuous casting process of heavy rail steel, problems of center segregation, center porosity, and shrinkage cavity of the bloom occur, which notably affect the billet quality of heavy rail steel. The soft reduction technique can effectively improve these problems, but internal cracks will appear, and the quality of the bloom will deteriorate if the parameters are not properly set. To examine the inner crack induced by the soft reduction of continuous casting bloom, this study established a mathematical model for the soft reduction of a 230 mm×280 mm section bloom by the ABAQUS finite-element software. The thermal-stress coupling model was used to predict the inner crack of the heavy rail steel bloom, using the soft reduction model during the soft reduction process. First, the temperature at different central solidification fractions of 0.3 –0.7 in the bloom was calculated. The equivalent plastic strain that was located at the solidification front at different central solidification fractions was then calculated by the soft reduction model. Results indicated that the equivalent plastic strain at the solidification front in the bloom did not exceed the critical strain of 0.4% at the central solidification fractions with a reduction amount of 7 mm. Moreover, the inner crack did not occur at the solidification front. Simultaneously, the soft reduction model calculation with a different reduction amount was conducted at the central solidification fraction of 0.6. Results showed that the equivalent plastic strain at the solidification front exceeded the critical plastic strain of 0.4% when the reduction amount was more than 7 mm, which resulted in an inner crack. The greater the reduction amount, the more serious is the inner crack. Concurrently, industrial experimental results had a 收稿日期: 2021−09−29 基金项目: 国家自然科学基金资助项目（51834002）；中国博士后科学基金资助项目（2021M690371） 工程科学学报，第 43 卷，第 12 期：1679−1688，2021 年 12 月 Chinese Journal of Engineering, Vol. 43, No. 12: 1679−1688, December 2021 https://doi.org/10.13374/j.issn2095-9389.2021.09.29.003; http://cje.ustb.edu.cn