钢种初始凝固模式对连铸坯表面质量的影响  

Effect of initial solidification mode of steel grade on surface quality of continuous casting billets

作　　者：李伟[1,2] 李阳[1,2] 程常桂[1,2] 刘江傲[1,2] 李洋[1,2] 金焱 LI Wei;LI Yang;CHENG Changgui;LIU Jiangao;LI Yang;JIN Yan(Key Laboratory of Iron and Steel Metallurgy and Resource Utilization of the Ministry of Education,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China;Hubei Provincial Key Laboratory of Iron and Steel Metallurgy New Technology,Wuhan University of Science and Technology,Wuhan 430081,Hubei,China)

机构地区：[1]武汉科技大学钢铁冶金及资源利用省部共建教育部重点实验室,湖北武汉430081 [2]武汉科技大学钢铁冶金新工艺湖北省重点实验室,湖北武汉430081

出　　处：《钢铁研究学报》2023年第7期819-831,共13页Journal of Iron and Steel Research

基　　金：国家自然科学基金资助项目(51974213,52174324)。

摘　　要：连铸过程中铸坯表面常产生各种质量问题,严重影响铸坯质量和生产顺行,然而,钢种初始凝固模式的差异对铸坯表面质量缺陷的影响规律尚不够明确。选用一系列代表性钢种,利用JmatPro软件进行了热力学平衡相图和高温力学性能的计算,结合Fe-C-X多元伪平衡相图特征点的理论计算公式,综合研究不同钢种的初始凝固模式及其对铸坯表面质量的影响规律。结果表明,对4种不同凝固模式的钢种而言,低碳、亚包晶凝固模式的钢种铸坯的主要表面质量缺陷分别是皮下夹杂、表面纵裂,其主要原因是高温阶段的相变引起的极限屈服强度和相变应变的变化;过包晶与高碳凝固模式的钢种铸坯很少出现表面质量问题。因此,表面缺陷的发生概率由钢发生高温相变(L+δ→γ/δ→γ)时δ相的比例、温度区间及坯壳的相变应变程度共同决定。基于钢种凝固模式及其对铸坯表面质量的影响,预测可能出现的铸坯表面质量缺陷,并采取相关措施降低表面缺陷发生率,对提高连铸坯质量具有重要意义。Various quality problems often occured on the surface of the billet during continuous casting,which seriously affected the quality of the billet and the smooth flow of production.However,the pattern of the effect of differences in the initial solidification pattern of steel grades on the surface quality defects of cast billets was not clear enough.A series of representative steel grades were selected,and the calculation of thermodynamic equilibrium phase diagram and high temperature mechanical properties were carried out using JmatPro software,combined with the theoretical formulae for the characteristic points of equilibrium Fe-C-X pseudo-binary diagram,to comprehensively study the initial solidification modes of different steel grades and their influence laws on the surface quality of casting billets.The results show that for the four different solidification modes of steel grades,the main surface quality defects of casting billets of low-carbon and hypo-peritectic solidification modes are subcutaneous inclusions and surface longitudinal cracks,which are mainly caused by changes in ultimate yield strength and phase strain due to phase transformation in the high-temperature stage;the surface quality problems of casting billets of hyper-peritectic and high-carbon solidification modes rarely occur.Therefore,the probability of occurrence of defects on the surface of the cast billet is jointly determined by the proportion of the δ phase when the steel undergoes a high-temperature phase transformation(L+δ→γ/δ→γ),the temperature interval and the degree of phase strain in the billet shell.Based on the solidification mode of steel grades and its influence on the surface quality of casting billets,it is important to predict the possible surface quality defects of casting billets and take relevant measures to reduce the incidence of surface defects to improve the quality of continuous casting billets.

关 键 词：初始凝固模式 铸坯 表面质量缺陷 高温相变 钢种成分 

分 类 号：TF777[冶金工程—钢铁冶金]