【作者】 刘旭兰；

【导师】 吴晓东；

【作者基本信息】 江苏大学 ， 钢铁冶金， 2009， 硕士

【摘要】 本文针对南钢电炉炼钢厂冶炼GCr15轴承钢的EAF-LF-VD-CC现行工艺与条件,采取系统取样、综合分析等方法对轴承钢精炼过程中非金属夹杂物的数量、大小、类型及分布的演变进行了全面研究,同时分析了轴承钢中氧含量及析出夹杂物成分的影响因素。研究表明:（1）VD处理后夹杂物数量比LF处理后略有减少,成材试样中夹杂物数量比VD处理后的数量减少显著。其中,LF工位夹杂物数量为3.5个/mm²,VD工位夹杂物数量为3.0个/mm²,成材试样中夹杂物的数量为1.4个/mm²;（2）LF处理后钢中非金属夹杂主要为三氧化二铝、硅铝酸盐、硫化物、点状不变形夹杂及铬铁酸盐夹杂;VD处理后没有再发现铬铁酸盐夹杂,钢中非金属夹杂主要为三氧化二铝、硅铝酸盐、硫化物和点状不变形夹杂;成材试样中夹杂物种类进一步减少,主要为硅铝酸盐和硫化物夹杂;（3）对100炉钢的A、B、D类夹杂物评级结果显示A、B类夹杂物均符合国际业内普遍类夹杂物的细系有不合格炉次,不合格炉次占总炉次的1%。3类夹杂物评级结果的平均值均符合国际业内普遍要求。（4）必须加强精炼炉脱氧制度,控制钢液中铝含量在0.025%左右;降低硫含量在0.0009%以下,以减少硫化物夹杂。（5）热力学计算结果表明,1823K[Si]为0.21%,当只有铝参与GCr15脱氧时,若α[Al]>0.000375%,将析出Al₂O₃;若α[Al]<0.000166%,将析出SiO₂:若α[Al]介于二者之间,将析出A₃S₂。当钢中有钙存在时,α[Al]=0.01%,若α[Ca]>10^-1.4将生成C₁₂A₇;若10^-4.9<α[Ca]<10^-1.4将生成CA₆;若10^-7.9<α[Ca]<10^-4.9将生成CA₂,若α[Cal<10^-7.9将生成CA;（6）实验结果显示,当R>5,CaO/Al₂O₃控制在1.7-1.8之间时,这时渣中的Al₂O₃大约在30%左右,有利于控制钢氧含量和夹杂物。更多还原

【Abstract】 Basing on the bearing steel refining process of EAF-LF-VD-CC and the current condition of Nanjing Iron & Steel Union CO.,LTD electrode furnace factory, this subject researches on the transmition rules about nonmetallic inclusions’ amount, size, type and distribution comprehensively by the way of systeme sampling and compositive analysis. Mean while the infl uence of oxygen content in bearing steel is also analisysed. Results show that:（1） The number of inclusions in the steel treated by VD are less than that treated by LF, the number of inclusions in the rolled product reduces sharply than that in the VD procedure. The number of the inclusions in LF procedure is 3.5/mm², which in VD procedure is 3.0/ mm², while in the rolled product is 1.4/mm².（2） Inclusions in the steel after LF procedure are mainly Al₂O₃, aluminosilicate, sulfide, ametabolic punctuate inclusions and chromium ferrate. After VD procedure there are no chromium ferrate but mainly Al₂O₃, aluminosilicate, sulfide and ametabolic punctuate inclusions. In the rolled product, kinds of inclutions reduce more, there are only aluminosilicate and sulfide.（3） Rating results of 100 furnaces steel show that A, B-type inclusions are in line with international requirements, D-type inclusions of fine lines have failed furnaces, which accounts for 1%. The average of the 3 Class inclusions are in line with international requirements.（4） The deoxidation system of refining furnace should be strdngthened, control the aluminum content in liquid steel at about 0.025%; The content of sulfur shoud be reduced to no more than 0.0009% to reduce the sulfide inclusion.（5） Thermodynamic calculations show that 1823K, [Si] relates to 0.21%, when only aluminum participates GCr15 deoxidization, ifα[Al] >0.000375%, it willprecipitate A1₂O₃; ifα[Al] <0.000166%, it will precipitate SiO2; ifα[Al] ranges between them it will precipitate A₃S₂.When calcium exists in the steel,α[Al] =0.01%, ifα[Ca] >10^-1.4 it will generate C₁₂A₇; if 10^-1.4<α[Ca] <10^-1.4 it will generate CA₆; if 10^-7.9<α[Ca]<10^-4.9 it will generate CA₂, and ifα[Ca] <10⁽-7.9 it will generate CA.（6） The experimental results show that when R> 5, CaO/Al2O3 is between 1.7 to 1.8, namely the Al₂O₃ is about 30% of the slag, it is favorable of controlling the oxygen content and inclusions in molten steel.更多还原