High speed casting of slabs has become one of the mandatory requirements for improvement of productivity and energy conservation of continuous casting processes. In high-speed casting, however, the lubrication ability of powder between the mold and the solidified shell is deteriorated by increasingcasting velocity, and the shell sticking in the mold results in breakout. In order to increase the casting speed, therefore, one of the most important factors is to improve lubrication in the mold.
First, we have carried out quantitative analyses on lubrication phenomena between mold and solidified shell and casting tests with an experimental continuous caster to make in-depth studies on the lubricationmechanism in the mold. Second, based on the results, we have proposed the new concept of mold oscillation for high speed casting.
The results are summarized as follows:
1) Liquid lubrication is dominant at the portion of closely below the meniscus than solid lubrication, and solid lubrication is dominant in the lower portion of the mould.
2) Non-sinusoidal oscillation mode is more effective to reduce the friction force between mold and shell than the conventional sinusoidal one.
By the application of the results of these fundamental studies, Fukuyama No. 5 continuous slab caster has been operating at a maximum casting speed of 2.5 m/min without occurrence of breakout, using anon-sinusoidal oscillation mode and powder with a low melting point and low viscosity.
