Refining theory and process of high-speed heavy-rail steel

Deoxidization,inclusion control and dehydrogenation were analyzed theoretically and the process experience was carried out to study the basicity of slag and the refining time during refining high-speed heavy rail steel. The theoretical analysis results indicate that high basicity slag is propitious to deoxidization in LF refining,and in order to prevent the precipitation of 2CaO·Al₂O₃·SiO₂,the contents of Ca and Al in the steel should be controlled to be lower. The process experience shows that the contents of total oxygen and hydrogen become already stable after 15 min refining and the slag basicity has not obvious influence on the deoxidization during RH refining,but high basicity induces to increase fragile inclusions in the steel. During high speed heavy rail steel refining,the slag with a higher basicity of 2.5 to 3.0 can be used in LF refining,but the basicity of slag should be suitably reduced (about 2.0) in RH refining,and the goals of deoxidization,inclusion control and dehydrogenation can come true after RH refining for 15 min.