A study on the field of fluid flow in 4-strand 25 t tundish with two different control devices has been carried out by 1 ： 2. 5 tundish water model test. And the effect of original tundish and improved tundish with modified diameter of hole for guide fluid at side of dam and its inclination

and added turbulent inhibitor on cleanliness of 325 mm x 280 mm casting bloom of bearing steel GCrl5 is tested by commercial production. Results show that the improved tundish is available to increase residence time of liquid steel in tundish

decrease dead volume fraction of tundish

increase removal rate of inclusion in liquid. Compared with the original tundish

the removal rate of total oxygen in liquid steel from improved tundish to bloom increases

the macro-inclusion content decreases by 44. 9% .