The sizing nozzle is the key refractory material of the non-stopper pouring system of the tundish of the small square billet continuous casting machine. It is used to control the flow of molten steel and ensure that the molten steel enters the crystallizer at a uniform speed. Its aperture remains basically unchanged during continuous casting.
It needs to be resistant to corrosion and thermally stable. Zirconium materials containing 60%-95% ZrO₂ are commonly used, and there are also composite materials (such as titanium nitride-zirconium oxide composites to improve performance).
According to the process/structure, it is divided into fully homogeneous (uniform composition, high cost), direct composite (the main body is zircon, the composite part contains high ZrO₂, one-time sintering, low cost but easy to crack), mosaic (the main body is high aluminum, the inner core is zircon, the cost is low but the core is easy to fall off), etc.; according to the ZrO₂ content, there are different specifications such as 60% and 65%.
Suitable for open pouring of small billet continuous casting. Since long/immersed nozzles are not suitable for small billets, they rely on flow control to ensure stable casting speed. However, problems such as diameter expansion and cracking may affect continuous casting during use, which promotes continuous improvement of materials and structures.
