Effect of Steel Cleanliness on the Clogging of the Submerged Entry Nozzle During the Casting of Titanium Bearing Stainless Steel

摘要

Ti stabilized stainless steels have been widely used in today's development due to the excellent corrosion resistance. However, it is well-known that there are some important problems to be overcome in the production process [1]: First, the clogging of submerged nozzle leads to casting or operational difficulties and affects the productivity of continuous cast steels. Second, the occurrence of skin laminations or line defects on the rolled material results in serious influence on the quality of the products. While laminations or line defects on the rolled plate surface are associated with the clogging or lump formation at the caster. In order to decrease the damage from the clogging of the submerged entry nozzle (SEN) of the Ti stabilized stainless steels during continuous casting process, many works have been done. Maddalena at el. [2] have reported that TiN, Al_2O_3 and MgO- Al_2O_3 could lead to serious nozzle blocking. Kim at el. [3] have investigated the submerged nozzle clogging of SUS409 stainless steel, it was found that there was a layer of TiO_x surrounded by a certain amount of cold steel on the inner wall of the nozzle, and they supposed that the formation of TiO_x layer increased the heat transfer between liquid steel and nozzle, which promoted the cooling and adhesion of liquid steel. The work of Hasegawa [4] showed that the major deposited materials were made up of A_2O_3 and TiN inclusion in the ladle or tundish, which deposited on the nozzle surface during passing through the immersed nozzle.