钢液钙处理过程有效钙硫比对303 t超大钢锭中硫化物形貌的影响  

Effect of effective Ca/S ratio on sulfide morphology in a 303-ton heavy steel ingot with calcium treatment in molten steel

作　　者：周秋月 任英[1] 巴钧涛 张立峰 ZHOU Qiuyue;REN Ying;BA Juntao;ZHANG Lifeng(School of Metallurgy and Ecological Engineering,University of Science and Technology Beijing,Beijing 100083,China;College of Mechanical Engineering,Yanshan University,Qinghuangdao 066004,China;School of Mechanical and Materials Engineering,Beijing North China University of Technology,Beijing 100144,China)

机构地区：[1]北京科技大学冶金与生态工程学院,北京100083 [2]燕山大学机械工程学院,秦皇岛066004 [3]北方工业大学机械与材料工程学院,北京100144

出　　处：《工程科学学报》2024年第4期715-722,共8页Chinese Journal of Engineering

基　　金：国家重点研发计划资助项目(2023YFB3709900);国家自然科学基金资助项目(U22A20171)。

摘　　要：通过工业实验研究了钙处理对303 t的16Mn重型管板铸锭中硫化物形貌的控制.未钙处理的锻件缺陷主要分布在轴向上靠近顶部、径向上在距中心1/2以内位置,缺陷主要为大尺寸Ⅱ类MnS夹杂物.采用Micro-CT检测了铸锭顶部中心位置MnS夹杂物三维分布,夹杂物为长条状和片状,数密度为0.77 mm^(-3),最大直径为1370μm.在真空脱气后对钢液进行钙处理,钙处理不仅将钢液中原生Al_(2)O_(3)夹杂物改性为液态钙铝酸盐,并且钙会在钢液凝固和冷却过程中优于锰先与硫结合生成CaS.通过FactSage热力学计算得到,钙处理将MnS夹杂物的析出温度由1244.7℃降低至1227.9℃,同时减少了MnS夹杂物析出量.钙在改性硫化物之前先改性了钢中氧化物,因此提出了有效钙硫比Ca/Seff.用来表征钙处理对硫化物形貌的影响,Ca/Seff.的含义为改性硫化物的有效钙和钢中硫的原子浓度比,可以直接根据钢液的总氧T.O含量、总硫T.S含量和总钙T.Ca含量计算得到,此公式适用于硫质量分数小于30×10^(-6)的低硫钢.随着钢中Ca/Seff.增加,铸锭顶部硫化物长宽比逐渐减小.钙处理后钢中有效钙硫比Ca/Seff.应大于0.8,铸锭顶部硫化物平均长宽比小于1.2,CaS和MnS复合硫化物以钙铝酸盐夹杂物为核心析出,硫化物为球形且尺寸显著减小,此时钙处理改性铸锭中硫化物效果较好.This paper investigated the effect of calcium treatment on the sulfide morphology of 303-ton 16Mn tube sheet ingots through industrial experiments.The defects in forgings without calcium treatment were mainly distributed axially near the top of the ingot and radially within half of the ingot center.The defects were mainly caused by large-size type II MnS inclusions.The three-dimensional distribution of MnS inclusions in the radial center of the ingot top was detected using a Micro-CT,and the MnS inclusions were mainly long strips and flake-shaped.The number density,average sphericity,and maximum diameter of the MnS inclusions were 0.77 mm-3,0.53,and 1370μm,respectively.In the industrial experiments,calcium treatment of molten steel was performed after vacuum-breaking during VD(Vacuum degassing)refining.Thermodynamic calculations were performed using FactSage 7.1 software.Calcium treatment modified the original solid Al_(2)O_(3) inclusions into liquid calcium aluminate inclusions and reduced the precipitation temperature of MnS inclusions from 1244.7℃ to 1227.9℃.During the solidification and cooling process of the ingot,Ca preferentially combined with S to form CaS,which reduced the precipitation of MnS inclusions.Calcium modified the oxide inclusions in steel before modifying sulfides.Therefore,the effective calcium/sulfur ratio(Ca/Seff.)was proposed to characterize the effect of calcium treatment on the mor-phology of sulfides.Ca/Seff.is the atomic concentration ratio of effective calcium for modified sulfide to sulfur in steel.Ca/Seff.can be calculated by the total oxygen,sulfur,and calcium contents in steel.This formula is suitable for low sulfur steel with high cleanliness,and the mass fraction of sulfur in molten steel is>30×10^(-6).We analyzed the morphology of sulfide on the top of a Ca-treated heavy ingot.The effect of Ca/Seff.ratio on the morphology of the sulfide was studied by sampling every 1/4 from the radial center to the edge of the ingot.The aspect ratio of sulfide at the top of the ingot de

关 键 词：重型铸锭 钙处理 夹杂物 硫化物形貌 有效钙硫比 

分 类 号：TG142.71[一般工业技术—材料科学与工程]