Orientation electrical steel hot rolling process system
06 Dec 2023
Reading Volume :
GNEE Steel Cold Rolled Silicon Steel
First of all, the hot rolling heating temperature, MnS as inhibitor CRGO steel, MnS+AlN as inhibitor of Hi-B steel, in the continuous casting billet must be heated at high temperature, so that the casting billet > 1μm of coarse MnS solution (mainly in the thickness of the billet plate isaaxial crystal center zone), In the hot rolling process, the fine dispersed MnS (10~1000 angstrom) of £50nm is precipitated, so the heating quality directly affects the magnetic level of the post-process. The heating temperature of the steel casting billet is required to be 1360~1380℃ (the solid solution temperature of MnS in the equilibrium state is 1320℃). Because the content of Mn and C in Hi-B steel is higher than that in Q steel, the heating temperature of the casting billet is required to be 1380~1400℃. The slab requires a uniform temperature in each part to avoid magnetic fluctuations and the appearance of black marks caused by the uneven temperature of the upper and lower slab. The rough rolling process is because the fine MnS is precipitated in the finishing rolling process, so it is necessary to control the temperature, time and thickness of the thin slab after the rough rolling and before entering the finishing mill (MnS begins to precipitated at about 1200 ° C, and the precipitation speed is the fastest at 1100~1150 ° C when the number of γ-phases is the most, and the precipitation is basically stopped at < 950 ° C). Therefore, high-speed rolling under high pressure rate is used in rough rolling to ensure that the temperature of thin slab is as high as possible (RT4min control in hot rolling process is mainly to ensure that the temperature entering the finishing rolling is greater than 1160±20℃, Q steel is currently ³1180℃, NQ08³1190℃, Hi-B³1200℃).
Finishing is to control the temperature of finishing rolling and finishing rolling. The opening temperature of Q steel is 1160±20℃, and the final rolling temperature is controlled above 960℃. Hi-B steel opening temperature > 1190℃, final rolling temperature > 960℃, generally controlled above 980℃; In the finishing rolling process, the main purpose is to produce a large number of dislocations in the rolling process, so that it becomes the precipitation core of MnS, and promote the MnS to be finer and more uniform precipitation in a fine dispersion. Dynamic recrystallization is realized in the rolling process to completely destroy the columnar crystals in the casting billet and fully recrystallize. Immediately after finishing rolling, water is sprayed to cool to about 550℃ for coiling: the carbide is dispersed in the grain (needle-like Fe3C), which acts as an additional inhibitor. The precipitate of AlN can be prevented by quenching after rolling.
