Na_(2)O对超高碱度连铸保护渣性能的影响  

Effect of Na_(2)O on properties of ultra-high basicity continuous casting mold fluxes

作　　者：潘伟杰 李民 朱礼龙 何生平[1,2] PAN Wei-jie;LI Min;ZHU Li-long;HE Sheng-ping(College of Materials Science and Engineering,Chongqing University,Chongqing 400044,China;Chongqing Key Laboratory of Vanadium-Titanium Metallurgy and Advanced Materials,Chongqing University,Chongqing 400044,China;Chongqing University of Science and Technology,Chongqing 401331,China)

机构地区：[1]重庆大学材料科学与工程学院,重庆400044 [2]钒钛冶金及新材料重庆市重点实验室,重庆400044 [3]重庆科技学院,重庆401331

出　　处：《钢铁》2022年第1期93-101,共9页Iron and Steel

基　　金：国家自然科学基金资助项目(51874057,52074054);重庆市自然科学基金资助项目(stc2020jcyj-msxmX0605);攀西试验区重大科技攻关资助项目(1840STC30699)。

摘　　要：在包晶钢连铸过程中,裂纹类缺陷频繁出现。生产实践表明,采用结晶性能较强的保护渣可以有效减少纵裂纹的发生,但会恶化保护渣的润滑功能。近年来,超高碱度保护渣由于兼具开始结晶温度低、结晶速率快的特点,可以成功协调包晶钢连铸过程中润滑与传热的矛盾。但在超高碱度条件下,有关组分对保护渣结晶性能的影响研究不多,且相应的熔渣结构特征也鲜有报道。Na_(2)O作为保护渣中一种常见的组元,对调节保护渣性能具有重要作用。论文采用半球点熔化温度测试仪、旋转黏度计以及高温原位结晶性能测试仪分析了超高碱度下(综合碱度R=1.75)Na_(2)O对连铸保护渣熔化流动特性以及凝固结晶性能的影响规律和作用机制。研究结果发现,随着Na_(2)O含量增加,保护渣的黏度(1300℃)、熔化温度、转折温度和结晶温度都呈下降趋势,结晶速率呈现先减小后增大的趋势,当Na_(2)O质量分数为6%时结晶速率最低。此外,研究还发现超高碱度保护渣中主要析出相为枪晶石(Ca_(4)Si_(2)F_(2)O_(2)),随着Na_(2)O含量进一步增加,渣中出现新的结晶相CaF;和Na_(2)CaSiO;F。During the continuous casting of peritectic steel,defects of longitudinal cracks of casting strands frequently appear.Production practice shows that mold fluxes with strong crystallinity can effectively reduce the occurrence of longitudinal cracks,but it will deteriorate the lubrication function of mold fluxes.In recent years,the ultra-high basicity continuous casting mold fluxes have the characteristics of low initial crystallization temperature and fast crystallization rate,which can successfully balance the contradiction between lubrication and heat transfer in the continuous casting of peritectic steel.However,there are few studies on the effects of related components on the crystallization properties of the ultrahigh basicity mold slag,and the corresponding structural characteristics are also rarely reported.Na_(2)O is a common component element in mold fluxes and plays an important role in adjusting the properties of mold fluxes.The effect and mechanism of Na_(2)O content on the melting flow characteristics and solidification and crystallization properties of continuous casting mold fluxes at ultra-high basicity(R=1.75)was analyzed by hemispherical point melting temperature tester,rotational viscometer and high temperature in-situ crystallization performance tester.The results showed that the viscosity(1300℃)of mold fluxes,melting temperature,break temperature and crystallization temperature all decreased with the increase of Na_(2)O content,while the crystallization rate first decreased and then increased,and the crystallization rate was the lowest when mass percent of Na_(2)O was 6%.In addition,it is found that the main precipitates in the ultra-high basicity mold flux were gun spar(Ca_(4)Si_(2)F_(2)O_(2)).With the further increase of Na_(2)O content,the new crystalline phases CaF;and Na_(2)CaSiO;F appeared in the mold flux.

关 键 词：保护渣 Na_(2)O 超高碱度 转折温度 结晶性能 

分 类 号：TF777[冶金工程—钢铁冶金]