90t BOF-LF-VD工艺冶炼GCrl5轴承钢的氧化物夹杂变化行为

GCr15钢的生产流程为90t转炉-LF-VD-250mm×280mm方坯连铸-轧制。转炉出钢加铝脱氧,LF由高碱度渣/%:55~58CaO,3~10MgO,12~16SiO₂,16~24Al₂O₃,≤1（MnO+FeO）]精炼,LF喂Al后TO]为14×10^-6,LF终点TO]10×10^-6。采用SEM（扫描电镜）+EDS（能谱仪）的方法,研究了线材中超标DS类夹杂物的成分分布,发现夹杂物中心以复合氧化物CaO-MgO-Al₂O₃为主,外围包裹少量CaS;这些氧化物中,Al₂O₃含量约占65%,分布最为均匀;CaO含量约占20%,MgO含量约占15%。统计分析结果表明,VD真空处理后每平方毫米13μm以上大颗粒夹杂物数量增至7,软吹后降至2.1,线材中1/3大颗粒夹杂物来源于钢包渣带入。

Behavior of Variation of Oxide Inclusions in Bearing Steel GCrlS Steelmaking by 90t BOF-LF-VD Process

The production flowsheet for steel GCrl5 is 90 t converter-LF-VD-250mm x280mm bloom casting-rolling process. With adding aluminium to deoxidize during converter tapping and refining by high basicity slag /% : 55 ? 58CaO, 3 ~ l0MgO, 12~ 16SiO₂, 16~24A1₂O₃, ≤ 1 (MnO + FeO) ], the T 0] after feeding Al in LF process is 14 x 10^-6 , and the TO] at end of LF refining is 10 x 10^-6. With using SEM (scanning electron microscope) and EDS ( energy dispersive spectroscope) to study the composition distribution of unqualified large DS series inclusions in rod products, it is found that at the center of inclusion the main composition is compound oxide CaO-MgO-Al₂O₃，outside is wrapped by a small amount of CaS, in this oxides the A1₂O₃ content is up to about 65% with even distribution, the CaO content is about 20% and the MgO content is about 15%. Statistics analysis results show that after VD vacuum treatment the number o£ diameter more than 13μm  large inclusions per mm² increases to 7, after soft stirring that decreases to 2. 1, arid in rod products the one of three large inclusions come from ladle slag.