高铝钢用低反应型保护渣成分对其黏度的影响

Review on effect of composition on viscosity of low-reactive mold flux for high-Al steel

汽车轻量化有助于保护环境、节约能源,高铝钢有利于减轻汽车质量同时维持强塑性。但由于连铸过程中传统结晶器保护渣界面反应的制约,高合金钢铸坯质量和操作流畅性受到很大影响,引起裂纹、漏钢等问题。不仅会造成安全事故,还会增加成本。低反应型CaO-Al_(2)O_(3)系保护渣相对于传统保护渣,SiO_(2)质量分数在6%~10%之间,[Al]和(SiO_(2))渣钢界面反应程度显著减弱,具有提高铸坯质量和确保操作顺行的潜力。设计此类保护渣时应该考虑渣钢界面反应、渣中元素向钢液中富集对铸坯质量的影响以及可能的结晶相种类。探讨了低反应型保护渣中成分对黏度变化机制的影响,即熔渣结构的变化、渣系过热度的变化和结晶相的变化。分别讨论了CaO/Al_(2)O_(3)、B_(2)O_(3)、Na_(2)O、Li_(2)O和CaF_(2)在CaO-Al_(2)O_(3)渣系中的作用,旨在为满足高铝钢连铸生产的新一代低反应型保护渣系的设计与优化提供思路与便利。

High aluminum steel helps to reduce the weight of automobile while maintaining the strength and elongation of product. Lightweight automobiles in favor of protecting the environment and saving energy. However, due to the restriction of the interface reaction of the mold flux in the continuous casting process, the quality of high-Al steel blank and smooth operation are greatly affected, causing problems such as cracks and breakout. It will not only cause safety accidents, but also increase costs. The low-reactive CaO-Al_(2)O_(3) mold flux with SiO_(2) content of 6%-10% compared to traditional mold fluxes, and the level of interface reaction between [Al] and(SiO_(2)) slag-steel is significantly weakened, which has the potential to improve billet quality and ensure smooth operation. When designing this type of mold flux, the influence of the slag-steel interface reaction, the diffusion of boron from flux to steel due to the slag-steel reaction between B_(2)O_(3) and dissolved aluminum, and the kinds of crystalline phases should be considered. The influence of the composition of low-reactive mold flux on the viscosity change mechanism was investigated, including the change of slag structure, the degree of superheat and crystalline phase. The effects of CaO/Al_(2)O_(3), B_(2)O_(3), Na_(2)O, Li_(2)O and CaF_(2) in the CaO-Al_(2)O_(3) slag system are discussed, aiming to provide ideas and convenience for designing and optimizing the new generation of low-reactive mold flux system that meet the demand of the continuous casting of high-aluminum steels.