1) Air bubbles, through pores

Definition and characteristics: irregular round or strip cavity protrusions on the surface of plates and strips. The raised edges are smooth, the plates are asymmetrical up and down, and the distribution is irregular.

The main reasons: the gas content of the ingot is too high; the surface of the ingot is uneven and unclean, and the depth of the surface segregation is deep; the amount of milling surface is small or the surface is defective, such as: dents or deep milling cutter marks.

2）light and dark stripes

Definition and characteristics: light and dark stripes parallel to the rolling direction on the surface of plates and strips.

The main reasons: the surface quality of the ingot is poor, and the surface is not milled before hot rolling; the surface structure of the slab has coarse grains or segregation bands.

3）peeling

Definition and characteristics: Local layering on the surface of sheet and strip. The layers are thin, and the cracks turn up.

The main reasons: the flatness of the ingot is poor; the milling surface is not very thorough.