小方坯流程高品质轴承钢工艺

相比于电炉冶炼和大方坯流程，采用转炉冶炼加小方坯流程具有更低的生产成本。根据天钢的实际生产情况，对采用“铁水脱硫扒渣→转炉冶炼→LF造渣精炼→VD真空精炼→小方坯连铸”流程生产高品质轴承钢的关键技术进行研究。分析冶炼过程钢水及连铸坯中夹杂物可知：随着LF炉炉渣碱度的升高，钢液中wT［O］大幅降低，控制炉渣碱度R在一个较高范围（7.0~9.0）对于控制钢液中wT［O］很重要；LF精炼初期，夹杂物中Al2O3含量较高，随着精炼的进行夹杂物向着CaO-Al2O3-MgO系和Al2O3-MgO系方向夹杂物发展；VD真空处理促进钢-渣-夹杂物间反应向平衡方向移动，夹杂物接着向CaO-Al2O3-MgO系方向发展，夹杂物中CaO含量增加；在小方坯连铸过程中，采用两级电磁搅拌加低拉速、低比水量的模式获得了较小的碳偏析度。

High-quality bearing steel with the billet caster process

Compared to the EAF and bloom process, converter and billet process for smelting bearing steel has the advantage of low production cost. Based on the actual production in Tianjin Iron and Steel Company, the research on the key technique during the process "hot metal pre-desulfurization-converter smelting-LF refining-VD refining-billet casting" has been undertaken. By taking samples systematically and analyzing the inclusion of the samples during the process, the following conclusions were obtained. The wT［O］ decreased with the increase of basicity of slag (R). The optimum basicity of slag ranged between 7.0 and 9.0. In the early stage of LF refining, the Al2O3 was high in the inclusion; during the process of refining, the composition of inclusion developed to Al2O3-MgO and CaO-Al2O3-MgO; the VD treatment promoted the steel-slag reaction to the balanced direction and the content of CaO in inclusion increased. In the process of billet casting, the method of two-stage electromagnetic stirring, lower casting velocity and smaller ratio of water spray obtained lower degree of carbon segregation.