The iron oxide on GB/T 700 Q235B carbon steel plate

GB/T 700 Q235B carbon steel plate needs to be heated at high temperature before hot rolling.

Because Q235B steel is exposed to oxidizing gas at high temperature, thick iron oxide will be produced on the surface of Q235B carbon steel plate.

The continuous casting billet needs to be descaled by heating furnace before entering the rolling mill.

If the surface iron oxide cannot be completely removed, it will have a certain negative effect on the surface quality of Q235B steel plate.

The quality of Q235B carbon steel plate has been seriously affected. The surface ferric oxide of Q235B steel has the characteristics of high hardness and hard pickling.

The main reason for the generation of iron oxide on the surface of GB/T 700 Q235B carbon steel plate are as below:

(1) the contact degree of O2 and the springback temperature of different parts of Q235B carbon steel plate after rolling is different.
Due to the coupling of two factors, the thickness of iron oxide on the side is larger than that in the middle, showing a trend of increasing first and then decreasing later.

(2) the ferric oxide of hot-rolled Q235B steel plate is mainly composed of FeO, Fe3O4 and Fe2O3.
The breaking of FeO during the final rolling process are the direct causes of iron oxide.

Therefore, on the basis of ensuring the performance of GB/T 700 Q235B carbon steel plate, it is necessary to increase the high pressure water descaling pressure before finishing rolling and increase the final rolling temperature.