Subentry Nozzles (SEN) for Continuous Casting

A SEN is a refractory nozzle that connects the tundish to the casting mould and discharges the steel stream below the mould slag line. The submerged discharge eliminates splashing, suppresses surface waves, and prevents reoxidation. SENs are mandatory for high-quality slab, bloom and beam-blank continuous casting.

Body is alumina-graphite (Al₂O₃-C) with 25–30% graphite. The slag line and the discharge ports are typically reinforced with zirconia-graphite (ZrO₂-C) for slag corrosion resistance. The bore is often lined with a low-carbon, anti-clogging insert to reduce alumina build-up during aluminium-killed steel casting.

In aluminium-killed steel, alumina inclusions tend to deposit on the SEN bore wall, eventually shutting flow. Anti-clog SENs use calcium-treated bore liners, special carbon-free inserts, or argon-purging through the bore wall. Argon-purged designs reduce clogging rate but require gas piping and flow control. Bore liner selection is matched to the steel grade.

Standard alumina-graphite SENs handle 4–8 heats per submerged immersion. ZrO₂-C reinforced SENs reach 8–12 heats in carbon steel. Heat-by-heat changing is also common in special steels and stainless. Service life is limited by slag-line erosion, bore alumina build-up, thermal cycling, and operator handling at change-out.

Common designs: bottom-only (most common), straight side ports (slab caster), angled side ports (5–35° down-angle for mould flow control), and slot-type for thin-slab casting. Port geometry is selected based on caster width, casting speed, and mould flow profile target. We supply SENs in all standard port configurations.

Pricing is per piece, depending on length, bore diameter, port geometry, and reinforcement (carbon, zirconia-carbon, anti-clog liner). A standard alumina-graphite SEN for a billet caster is the most economical. Premium ZrO₂-C anti-clog SENs for slab casting are 3–5× the price. Volume contracts deliver 15–25% saving over spot pricing.