Abstract：Aiming at the surface hairline crack defects often occurred in the production of the hot rolling plate BG490CL and galvanized steel sheet St02Z in Benxi Iron and Steel (Group) Co., Ltd. The metallographic structure, high scanning, variation of the inclusions and metallurgical quality were comprehensively detected and analyzed by using the physical equipment such as microscope and SEM and observing the macro characteristics and the microstructure of defects from different angles in detail. Eventually, it concluded that the hairline crack was induced by the remained deep vibration mark of casting slab, which can be avoided by determining the reasonable liquid level fluctuation of the steel in casting.
2016, Vol. 26 
