Hot Rolling Process System For Oriented Silicon Steel

Hot rolling heating temperature

CGO steel with MnS as the inhibitor and Hi-B steel with MnS + AlN as the inhibitor must be heated at high temperature in the continuous casting billet, so that 1μm of coarse MnS solid solution is > in the casting billet (mainly in the equiaxed crystal center area in the thick direction of the casting billet), and then precipitated with a fine diffuse MnS (10~1000 angstroms) of £50nm during the hot rolling process, so the heating quality directly affects the magnetic level of the post-process.

The heating temperature of steel billet is required to be 1360~1380 °C (the solution temperature of MnS in equilibrium is 1320 °C).

Because the content of Mn and C of Hi-B steel is higher than that of Q steel, the heating temperature of the casting billet is required to be 1380~1400 °C.

The slab requires uniform temperature in all parts to avoid magnetic fluctuations and black marks caused by uneven temperature of the upper and lower slabs.

Coarse rolling

Since the fine MnS is precipitated during the finishing process, it is necessary to control the temperature, time and thickness of the thin slab after roughing and before entering the finishing mill (MnS starts from about 1200 °C, and the precipitation speed is fastest at the temperature when the number of γ-phases is the largest at 1100~1150 °C, and the precipitation

Finishing rolled
Control the temperature of finishing rolling and final rolling, the opening temperature of Q steel is 1160±20 °C, and the final rolling temperature is controlled above 960 °C;

The opening temperature of Hi-B steel is > 1190 °C, the final rolling temperature is > 960 °C, and it is generally controlled above 980 °C;

In the finishing process, the main purpose is to generate a large number of dislocations during the rolling process, so that it becomes the precipitation core of MnS, and promotes the finer and more uniform precipitation of MnS in a fine diffusion form.

Dynamic recrystallization is achieved during the rolling process to completely destroy the columnar crystals in the billet and fully recrystallize.

Winding
Immediately after finishing rolling, water spray cools to about 550°C to take:

The carbide is dispersed and distributed in the grain (needle-like Fe3C), which acts as an additional inhibitor.

Quenching after rolling prevents the precipitation of AlN.