Novel insight into evolution behavior of non-metallic oxides in tire cord steel based on dissolved oxygen obtained by electromotive force method
摘要
Non-metallic inclusions are a significant factor causing fractures during the manufacturing process of tire cord steel, and dissolution in the steel profoundly affects them. How the basicity and Al2O3 content in SiO2–CaO–Al2O3–MgO refining slag affect non-metallic inclusions in tire cord steel at 1873 K was investigated. A quantitative relationship has been established between the slag basicity and the dissolved oxygen content in steel. The results demonstrate that non-metallic inclusions in steel transform along SiO2–MnO–Al2O3 → SiO2–MnO system of inclusions. When the basicity is controlled within the range of 0.8–1.0, the corresponding dissolved oxygen content should be between 4 × 10−6 and 10 × 10−6. When Al2O3 content in the refining slag is maintained at 5%, and the slag basicity is controlled between 0.8 and 1.0, or if the slag basicity is precisely 1.0 with Al2O3 content kept below 11%, control over the plasticization of SiO2–MnO–Al2O3 system within the inclusions can be effectively achieved. Combined with thermodynamic calculation and measurement of the dissolved oxygen ([O]) activity in the steel, controlling SiO2–MnO–Al2O3-like inclusions in the plastic region range can be achieved by adjusting the refining slag composition.