无磁钢20Mn23AlV保护渣液渣和渣圈性能变化对连铸的影响

对高铝无磁钢20Mn23AIV(/%:0.14～0.20C、21.50～25.00Mn、1.50～2.50Al、0.04～0.10V)200 mm板坯连铸过程结晶器保护渣液渣和渣圈的化学组成、理化性能和结晶矿相进行了对比分析。保护渣原渣组成为(/%):31.91CaO、30.30SiO₂、6.58Al₂O₃、1.12MgO、3.02MnO、7.73Na₂0、7.10F。结果表明,连铸开浇后15 min,液渣和渣圈中的SiO₂含量分别降低至22%和18%, Al₂O₃含量分别提高至20.5%和25.5%,其碱度由原渣的1.05分别提高至1.7和2.0。此时液渣及渣圈的熔化温度和粘度大幅度增加,转折温度大幅度降低;渣圈的化学成分及理化性能的变化幅度均大于液渣。连铸开浇15 min后液渣及渣圈的成分与性能均趋于稳定。高熔点相钙铝黄长石的析出是促使渣圈形成的重要原因。

Effect of Properties Change of Mold Flux and Slag Rim on Concasting of Non-Magnetic Steel 20Mn23AlV

The chemical ingredient, physical-chemical properties and crystallized mineralogical phases of mold flux and slag rim for 200 mm slab of high aluminium non-magnetic steel 20Mn23AlV (% ： 0. 14 ~ 0. 20C, 21. 50 ~ 25.OOMn, 1. 50 ~2.50Al, 0. 04 ~0. 10V) during concasting has been compared and analyzed. The ingredient of mold original flux is (/%) 31.91CaO, 30. 30SiO₂, 6.58A1₂O₃, 1. 12MgO, 3.02MnO, 7. 73Na₂O, 7. 10F. Results show that after starting casting in 15 min, the SiO₂ content in mold flux and in slag rim respectively decreases to 22% and 18% , the Al₂0₃ content in that respectively increases to 20. 5% and 25. 5%, and the basicity of that increases from 1. 05 of original flux respectively to 1. 7 and 2. 0 ； this moment the melting temperature and viscosity of mold liquid flux and slag rim increase obviously while the break temperature decreases markedly ； the change range of ingredient and physico-chemical properties of slag rim are all larger than that of mold liquid flux； and as casting for more than 15 min, the ingredient and properties of mold liquid flux and slag rim tend to stability. The precipitation of high melting-point phase gehlenite is an important cause to form the slag rim in mold.