The surface presents a non-metallic inclusion in the form of dots, blocks or lines, which is intermittently or continuously distributed in the rolling direction, and has a color of good brown, dark gray or white. In severe cases, the steel plate has holes, cracks, and broken bands.

When the steelmaking is poor, the slag is poor, the viscosity of the molten steel is large, the fluidity is poor, the slag can not float, and there are many non-metallic inclusions in the steel;

The casting temperature is low, the boiling is poor, and the inclusions are not floating;

continuous casting, the protective slag is brought into the steel;

Non-metallic materials in steel water tanks, steel ingot molds or injection pipes are not cleaned.

The defects are spot-like, and the general color is different from that of the steel strip, and it is mostly white and grayish white. The length is not very long, and it is mostly present in the head and the roof of the steel strip. When the degree is serious, the strips and holes are formed. It is divided into closed shape and open shape.

Due to inclusions in the molten steel during steelmaking, or scratches, chisel marks, etc. on the surface of the steel strip during hot rolling, when cold rolling, a spot-like trace is formed on the surface of the steel strip.

Manufacturer	Thickness	Width	Length of plate	Inner diameter of coil
	0.3-2.5mm	1000-1500mm	1000-6000mmDC01/ ST12	508mm/610mmCS TYPE A/B/C
Private factories	0.14-0.9mm	50/610/762/914mm