Ingot Casting

Continuous casting conquered the steel world — over 96% of global crude steel is now continuously cast — yet every serious steel country keeps an ingot route alive, and not as a museum. The reason is in the products: a 120-tonne turbine rotor, a reactor pressure-vessel shell course, a mill roll, a large marine crankshaft. These begin as single forgings heavier than any continuous caster section can supply — a forging needs an as-cast block of its own mass plus discard, and the largest casters top out around 400–500 mm sections, where big forging ingots run 50–600 tonnes. Below that hard size constraint sit softer niches: ultra-segregation-sensitive tool and high-speed steels (cast small precisely to control structure), remelt electrode stock for ESR/VAR (chapter 3), small-lot special grades whose order sizes never fill a caster sequence, and foundries' starting stock.

The economics divide cleanly. Continuous casting wins on yield (no per-piece crop head), labour, energy (no soaking of cold ingots when hot-charged), and surface; the ingot route wins where it is the *only* route (size), where lot flexibility beats line productivity, or where downstream remelting will rebuild the structure anyway. A modern special-steel works typically runs both: caster for the volume grades, an ingot bay — often automated far beyond its 1950s ancestor — for the heavy and exotic end.

For this pathway the ingot also earns its place as a teaching object: everything continuous casting does dynamically — solidification structure, segregation, shrinkage, inclusion behaviour — the ingot does statically, at full scale, readable in a sulphur print. Understand a big ingot and the caster's crater holds no mysteries.