The steel strip is stagnant for too long in the furnace and the surface is excessively oxidized, resulting in a gray surface on the steel strip. Sometimes it will appear rough spots on the face;

Due to insufficient dew point or unstable atmosphere in the furnace, the surface of the steel strip is bluish, yellowish and blackened.

Steel strip surface presents a brighter color, mechanical properties do not meet the requirements

Quality	GB/T 11253-2007 GB/T 5213-2001	JIS G3141-2005 JIS G3101-2004	EN 10130-2006 EN 10139-1998 DIN 1623-1986	ASTM A1008 / A1008M-05
Commercial Steel	Q195	SPCC(T)	DC01/ ST12	CS TYPE A/B/C
Drawing Steel	SC1 SC2 SC3	SPCD	DC03/ ST13	DS TYPE A/B
Deep Drawing Steel	SPCE	DC04/ ST14	DDS