Abstract：In view of the problem of surface longitudinal crack of sulfur-containing steel in bloom, metallographic and energy spectrum observations were made on the crack defects, and it was found that the longitudinal crack occurred after casting bloom out of mold. Through high temperature thermoplastic test determine the range of precipitation and organization, and analyses the influence of sulfur in steel high temperature thermoplastic and organizational precipitation range, the influence of the identified under 900 ℃ the third brittle interval, the formation of austenite grain boundary proeutectoid ferrite weaken the intensity of grain boundary, the thermal stress and organization stress, mechanical straightening stress under the influence of grain boundary cracking occurs. It is the root cause of longitudinal cracks on the surface of steel containing sulfur. On this basis, the optimization of protective slag, reconstruction of secondary cooling zone, heating of casting slab and heat preservation of pile cooling process were carried out. The results show that the longitudinal cracks on the surface of the bloom containing sulfur steel can be well controlled by increasing the basicity of protective slag, reducing the melting point and viscosity of protective slag, extending the length of secondary cooling zone, standardizing heating and cooling process. The grinding rate of round steel caused by longitudinal cracks was reduced from 20% to less than 5%.
刘亮. 大方坯含硫钢表面纵裂纹成因分析与控制[J]. 连铸, 2022, 41(3): 51-55.
LIU Liang. Analysis and control over formation cause of surface longitudinal crack for continuous casting bloom of sulfur bearing steel. CONTINUOUS CASTING, 2022, 41(3): 51-55.
2022, Vol. 41 
