Research on sulfur stability control in high sulfur plastic die steel
Based on typical defect detection and MnS precipitation behavior of high-sulfur plastic die steel,combined with thermodynamic calculation and industrial test,the sulfur stability control means in refining process of high-sulfur plastic die steel were explored.The results show that MnS inclusion is one of the causes of cracks.MnS began to precipitate at 1 708 K,and dislocation nucleation occurred first.The fastest precipitation temperature of MnS for grain boundary nucleation is 1 573 K,and it grows obviously during the heating process of billet.Based on the theoretical study of physicochemical properties,sulfur capacity and sulfur distribution ratio of refining top slag of high-sulfur plastic die steel,the optimal refining top slag composition ranges are 1.55≤(w(CaO)/w(SiO2))≤1.7、24％≤w(Al2O3)≤28％、1.4≤(w(CaO)/w(Al2O3))≤2.3、7％≤w(MgO)≤9％and 2.5％≤∑w(FeO+MnO)≤4.0％.After the optimization of refining top slag composition and refining process,the average reduction of sulfur mass fraction from VD station to tundish was reduced from 108 × 10-6 to 30 × 10-6,and the average mass fraction of Als loss was reduced from 24.9 × 10-6 to 14.2 × 10-6.Therefore,the sulfur stability and Als loss in VD to tundish were greatly improved.
high sulfur plastic die steelMnSprecipitation behaviortop slagsulfurstability
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NSTL
万方数据
维普
