Abstract: Typical cracks and microstructure were observed and analyzed by SEM, many precipitates were found along the grain which plays a significant role on the crack formation of boron micro-alloyed steels. High temperature mechanical properties of three boron micro-alloyed steels were tested by Gleeble-3800 thermal simulation testing machine and the actual slab temperature was measured in the continuous casting process. It shows that the external factors of transverse corner cracks is the deep oscillation mark and the straightening or bending process on low ductility temperature. According to the above research and analysis, the optimization scheme was concluded. The main optimization is adding titanium to nitrogen fixation after deoxidation by adding aluminum. The oscillation parameters was optimized as supplement. At last the crack rate of boron micro-alloyed steels was successful controlled from 10% to 1% .

Key words: boron micro-alloyed steel, transverse corner crack, precipitation, add titanium to nitrogen fixation