硫含量对Q235B钢连铸坯表面纵裂纹的影响

分析Q235B钢连铸板坯表面纵裂纹产生的原因,主要是钢中锰硫比偏低及结晶器液面波动较大。为提高钢中锰硫比,减轻结晶器液面波动,在铁水w(S)≥0.045%的情况下,铁水兑入转炉前应先尽可能扒除铁水表面的熔渣,转炉终点w(S)≥0.035%的炉次,出钢过程采取"渣洗"处理工艺,并适当增加Mn-Si合金,在连铸工序采取结晶器换渣操作,可减少板坯表面纵裂纹缺陷。

Effects of sulfur content on surface longitudinal crack of CC slab of steel Q235B

The present paper analyzes the origin of the surface longitudinal crack of CC slab of steel Q235B. It＇s determined that the primary causes to the crack are low Mn/S rate and fluctuation of the liquid level of the mould. For those heats the hot metal of w （S）≥0. 045% in order to raise the Mn/S rate in steel and reduce the fluctuation of the liquid level in mould, the molten slag on the surface of the hot metal has to be removed as much as possible before the hot metal is poured into the converter. ＂Slag washing＂ practice has to be adopted and proper amount of Mn-Si alloy have to be added into the hot metal in the process of tapping and slag change＂ practice has to be adopted in the continuous casting process as well for those heats of w（S）≥0. 035% at end of blow. Thereby the defect of surface crack of the slab can be reduced.