氧含量对超低碳钢炼钢连铸过程夹杂物演变的影响  

Effect of oxygen content on evolution of inclusions in ultra low carbon steel during steelmaking and continuous casting

作　　者：黄淑媛 罗钢[2] 杨健 徐刚军[2] 周军军[2] 郑庆 HUANG Shuyuan;LUO Gang;YANG Jian;XU Gangjun;ZHOU Junjun;ZHENG Qing(State Key Laboratory of Advanced Special Steel,School of Materials Science and Engineering,Shanghai University,Shanghai 200444,China;Hunan Valin Lianyuan Iron&Steel Co.,Ltd.,Loudi 417000,China)

机构地区：[1]上海大学材料科学与工程学院,省部共建高品质特殊钢冶金与制备国家重点实验室,上海200444 [2]湖南华菱涟源钢铁有限公司,湖南娄底417000

出　　处：《炼钢》2021年第4期38-48,共11页Steelmaking

基　　金：国家自然科学基金钢铁联合研究基金重点项目(U1960202)。

摘　　要：针对不同氧含量超低碳钢的炼钢和连铸过程,分析了钢中夹杂物的演变规律及其原因。钢中最常见的夹杂物从转炉终点的Al_(2)O_(3)-CaO-MgO-SiO_(2)复合夹杂物,变为RH进站和脱碳终点的Al_(2)O_(3)-MnO,再变为铝脱氧后和RH出站的Al_(2)O_(3)。由于连铸坯的冷却速度较慢,有利于TiN的充分析出,所以在中间包钢样中的TiN尺寸一般小于2μm,而在连铸坯中的TiN尺寸一般大于2μm;在中间包中常发现Al_(2)O_(3)-MnS复合夹杂,而在连铸坯中常发现Al_(2)O_(3)-MnS-TiN复合夹杂。中心夹杂物Al_(2)O_(3)尺寸较大时,Al_(2)O_(3)-TiN复合夹杂物的形状不规则;当Al_(2)O_(3)尺寸较小时,该复合夹杂的形状规则。因为大包钢水量为100 t时O31炉次中间包钢液氧质量分数(31×10^(-6))高于O_(2)2炉次(22×10^(-6)),所以大包钢水量为100 t和50 t时O31炉次中间包含Al_(2)O_(3)夹杂物的数量高于O_(2)2炉次。因为铸坯中心最后凝固,S、Mn、Ti、N等元素的偏析造成大量细小的MnS、TiN和TiN-MnS析出物的生成,所以铸坯宽度1/2处的夹杂物数量密度最多。For the process of steelmaking and continuous casting of ultra-low carbon steel with different oxygen contents, the evolution law of inclusions in steel were analyzed. The most common inclusions in steel change from the Al_(2)O_(3)-CaO-MgO-SiO_(2)composite inclusions at the end of converter to the Al_(2)O_(3)-MnO inclusions at the RH inlet and at the end of decarburization, and then to the Al_(2)O_(3) inclusions after aluminum deoxidation and at the RH outlet. Because the slow cooling rate in continuous casting slab is conducive to the full precipitation of TiN, the size of TiN in tundish steel sample is generally smaller than 2 μm, while the size of TiN in continuous casting slab is generally larger than 2 μm. The composite inclusions of Al_(2)O_(3)-MnS are often found in tundish, while the composite inclusions of Al_(2)O_(3)-MnS-TiN are often found in continuous casting slab. When the size of the central Al_(2)O_(3)inclusion is large, the shape of the composite inclusion of Al_(2)O_(3)-TiN is irregular;when the size of the central Al_(2)O_(3)inclusion is small, the shape of the composite inclusion of Al_(2)O_(3)-TiN is regular. Because the oxygen mass fraction of heat O31(31×10^(-6)) is higher than that of heat O_(2)2(22×10^(-6)) in tundish at liquid steel quantity of ladle is 100 t, the number densities of the composite inclusions containing Al_(2)O_(3) in tundish are higher than those of heat O_(2)2 at liquid steel quantity of ladle is 100 t and 50 t. Because of the final solidification in the center of the slab, the segregation of S, Mn, Ti, N and other elements results in the formation of a large number of fine MnS, TiN and TiN-MnS precipitates, the number density of inclusions at 1/2 of the slab width is the highest.

关 键 词：超低碳钢 夹杂物演变 热力学计算 氧含量 渣 

分 类 号：TF777[冶金工程—钢铁冶金]