过热度对12Cr2Mo1R大扁锭凝固过程中心宏观偏析的影响  

Influence of superheat on central macrosegregation of 12Cr2Mo1R steel heavy flat ingot during solidification

作　　者：孟庆勇[1] 王福明[1] 李长荣[2] 李梦龙[1] 庞瑞朋[2] 

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]北京科技大学材料科学与工程学院,北京100083

出　　处：《材料热处理学报》2015年第3期244-250,共7页Transactions of Materials and Heat Treatment

基　　金：国家自然科学基金(51374018;51174020);国家高技术研究发展计划项目(2013AA031601);中央高校基本科研业务费专项资金(FRF-SD-12-010A)

摘　　要：基于体积平均的两相数学模型,耦合求解温度场、流场和浓度场,模拟计算过热度对12Cr2Mo1R大扁锭凝固过程碳元素宏观偏析的影响。本模型将钢液密度设为依赖于温度和溶质浓度的函数。因而,可以综合考虑温度梯度、浓度梯度以及体积收缩等因素对钢液流动的作用,能够更加精确地预测凝固过程溶质元素分布。本次实验研究了过热度对凝固前沿温度梯度、凝固速率和钢液流动速率影响规律,以及最终碳元素宏观偏析情况。模拟结果表明:过热度的增加导致铸件表面区域凝固前沿温度梯度升高,而对中心线区域凝固前沿温度梯度的影响不显著;过热度对铸锭凝固速率的影响很小。此外,过热度的增加使得钢液流动速度相应增加,并使得固液两相区宽度相应的减小。铸锭凝固过程中碳元素宏观中心偏析总体表现为:当过热度<40℃时,增加过热度对加剧铸锭中心偏析不显著;然而,当过热度>40℃时,提高过热度使得铸锭中心偏析急剧恶化。Based on a volume-average two-phase approach,a fully coupled temperature,velocity and concentration fields model has been established for calculating the influence of superheat on central macrosegregation of 12Cr2Mo1R steel heavy flat ingot during solidification.Considering the significant influence of velocity field on solute transportation,the density of liquid steel was set as the function of temperature and concentration. Therefore,the flow caused by gravity,thermal gradient,solute gradient and volume shrinkage was comprehensively considered. In this work,the influence of superheat on the gradient of solidification front,solidification rate,mushy zone width and flow rate of liquid steel was investigated. The results indicate that with increasing of superheat,the gradient of solidification front near surface of the ingot increases,while the gradient of solidification front near the centerline of the ingot is almost invariant.Besides,changing of superheat has little effect on the solidification rate. In addition,with superheat rising,mushy zone is narrowed,and flow rate of liquid steel is promoted. Generally,when superheat is less than 40 ℃,central macrosegrgation is slightly increased with the rise of superheat. When superheat exceeds 40 ℃,central macrosegregation is sharply aggravated with the increase of superheat.

关 键 词：过热度 中心偏析 数值模拟 大扁锭 

分 类 号：TG244.3[金属学及工艺—铸造]