Hot Top

A hot top is a specialized refractory-lined component installed at the top of an ingot mold during steel casting. It functions as an insulating reservoir that maintains molten steel in a liquid state longer than the main mold body, promoting directional solidification from the bottom upward. This controlled solidification minimizes shrinkage cavities and pipe defects in the final ingot, improving yield and internal quality by concentrating shrinkage in the hot top section, which is later cropped and recycled.

The hot top operates on the principle of thermal insulation and controlled solidification. By using refractory materials with low thermal conductivity, it reduces heat loss from the molten steel at the top of the ingot mold. This creates a temperature gradient that encourages solidification to progress upward from the bottom of the ingot, ensuring that shrinkage porosity forms only in the hot top region rather than within the usable ingot body.