Decreasing Central Porosities in a Continuous Casting Thick Slab by Heavy Mechanical Reduction Near the Solidification End

In this study, the inner quality of a 400-mm-thick continuous casting slab was improved by heavy mechanical reduction. Heat transfer computation was performed to clarify the formation mechanism of the uneven solidification of the slab. It was found that the W-shaped solidification frontier in the slab width direction was closely related to unreasonable cooling. By optimizing the cooling, more synchronous solidification of the slab was realized. The original double-crater liquid core of the slab in the casting direction was prohibited, and the W-shaped solidification frontier along the slab width direction was modified into a flat “tongue.” The uniform solid fractions in the width direction favored the conduction of heavy reduction. It was found that the 20-mm reduction near the solidification end of the slab was efficiently permeated from the slab surface into the slab center, which greatly helped to “heal” the central porosities in the slab.