Casting technology of continuous casting bearing steel

At present, continuous casting and pouring methods are mostly used in steel production worldwide. The continuous casting process technology of bearing steel should generally include:

1) Tundish heating technology whose main purpose is to control the lower superheat of molten steel, it is possible to control the superheat of continuous casting bearing steel within the range of 5～10℃. At present, the plasma heating technology of tundish has been used in Japan and the United States. Steel mills in countries such as Italy, Germany, and France have been widely used in industry.

2) Slag detection and steel retention operation. There is a certain amount of steel retained in the German GMH, French Ascomeral ladle and tundish. The AMEPA device is installed at the bottom of the ladle to detect the amount of slag discharged from the ladle.

3) Pouring without oxidation protection in the whole process. The German GMH plant controls the N blowing flow rate of the protective pouring, and adopts the intermediate tank nozzle blowing N technology to prevent the nozzle from clogging; the French Ascomeral uses refractory protection sleeves between the ladle and the intermediate tank, between the intermediate tank and the mold O2 in an inert atmosphere is less than or equal to 0.2%.

4) The mold level is automatically controlled, and the French Ascomeral strictly monitors the mold level during pouring, and checks the erosion degree of the nozzle and plug after pouring.

5) Small amplitude and high frequency of crystallizer.

6) In order to obtain a large and uniform central equiaxed crystal zone for the electromagnetic stirring of the mold and the secondary cooling end stage, almost all continuous casting bearing steel manufacturers uses two electromagnetic stirring devices, thus, the crystal structure with uniform structure and no loose center can be obtained.

7) The soft reduction technology that takes control of the solidification process of the solidification end-place of the continuous casting billet as the main purpose, enable the center segregation degree of the continuous casting bearing steel billet to be controlled online, thus providing an effective way to solve the center carbon segregation of the continuous casting bearing steel.