Abstract: Aiming at controlling slab transverse corner crack of microalloyed steel containing niobium or titanium,the chamfered mould technology has been developed and applied on the Masteel slab continuous caster. The effect of chamfer structure on temperature of slab corner has been studied by establishing three dimensional steady heat transfer model and using the method of numerical simulation. The control effect for corner transverse cracks of slabs with different angle shape has been compared and analyzed through the industrial tests. The numerical simulation results showed that the corner temperature was obviously increased when the slab angle was changed from a right angle to an obtuse angle. The slab corner temperature will be increased from 788 ℃ to 1 091 ℃ above at a place where the distance from meniscus was 900 mm. The slab width corner temperature was 1 091 ℃, 1 128 ℃ and 1 110 ℃ when the slab width angle was 120°,125°and 125°respectively. Accordingly, the temperature of the slab narrow face angle was 1 254 ℃, 1 240 ℃ and 1 209 ℃respectively. Industrial test results showed that transverse corner cracks has been effectively controlled by using chamfered mould and soft secondary cooling process. The transverse corner crack ratio was the lowest when the angle of the slab width chamfer was 125° and the slab quality could meet the need of hot charging and direct rolling.

Key words: Chamfered mould, microalloyed steel, transverse corner crack, corner temperature, corner shape