Na2O对低碱度保护渣结晶性能的影响
EFFECT OF Na2O ON THE CRYSTALLIZATION PROPERIES OF LOW ALKALINITY MOLD FLUX
马坤霞 1王浩南 1郭银星 2王杏娟2
作者信息
- 1. 河钢集团唐钢公司,河北 唐山0630161
- 2. 华北理工大学冶金与能源学院,河北 唐山 063210
- 折叠
摘要
裂纹敏感性钢种所用连铸保护渣普遍通过提高碱度来增强结晶性能,但高碱度会使得铸坯与结晶器之间的润滑变差,增大铸坯表面产生缺陷的风险.设计低碱度保护渣,使其能够具有与高碱度保护渣同样的结晶性能,并同时保持良好的润滑性能,是协调裂纹敏感性钢种连铸过程中保护渣润滑性与控制传热关系的一项有效措施.本文采用SHTT-Ⅱ单丝设备,对不同Na2O含量保护渣进行结晶性能测试,并绘制TTT和CCT曲线;利用Scigress分子动力学软件进行模拟研究,发现随Na2O含量的增加,保护渣结晶温度升高,结晶率提升,孕育时间缩短,临界冷却速率逐渐增大,结晶出现变早,较易结晶.高温条件下熔渣结构体网络聚合度减小,黏度逐渐降低.在实验用Na2O含量范围内,当Na2O含量增加到15％时,在凝固过程中三配位氧个数增加150左右,有化合物生成.表明增加Na2O含量可以控制弯月面区域极冷条件下的传热,实现低温快速结晶.
Abstract
The continuous casting mould flux used in crack sensitive steel generally enhances the crystallization performance by increasing the alkalinity,but the high alkalinity will make the lubrication between the casting billet and the mold poor,and increase the risk of surface defects of the casting billet.It is an effective measure to coordinate the relationship between lubricity and heat transfer control in the continuous casting process of crack sensitive steel by designing low alkalinity mould flux to have the same crystallization property as high alkalinity mould flux and keep good lubrication property at the same time.In this paper,the crystallization properties of different Na2O content mould flux were tested by SHTT-Ⅱ monofilm equipment,and TTT and CCT curves were drawn.Scigress molecular dynamics software was used to simulate the results.It was found that with the increase of Na2O content,the crystallization temperature of the mould flux increased,the crystallization rate increased,the incubation time shortened,the critical cooling rate gradually increased,the crystallization appeared earlier,and the crystallization was easier.Under the condition of high temperature,the network polymerization degree of slag structure decreases and the viscosity decreases gradually.In the experimental Na2O content range,when the Na2O content is increased to 15％,the number of tricoordination oxygen increases by about 150 during the solidification process,and compounds are formed.The results show that increasing Na2O content can control the heat transfer under extremely cold conditions in the meniscus region and achieve rapid crystallization at low temperature.
关键词
保护渣/Na2O/低碱度/结晶性能/TTT/CCTKey words
mould flux/Na2O/low alkalinity/crystallization property/TTT/CCT引用本文复制引用
基金项目
国家自然科学基金资助项目(52374335)
国家自然科学基金资助项目(51974133)
出版年
2024
NETL
NSTL
万方数据