DP590钢夹杂物在精炼及浇铸过程中的演变行为

Evolution Behavior of Inclusion in DP590 Steel during LF Refining Process and Continuous Casting Process

围绕某钢铁企业生产的DP590钢中非金属夹杂物在精炼及浇铸过程中的演变行为,采用氧氮分析、显微夹杂统计及SEM-EDS能谱分析等手段进行了系统深入的研究。利用Fact-Sage软件计算并绘制了1 600℃时CaS-CaO-Al2O3三元相图,分析了精炼和连铸过程中夹杂物在CaS-CaO-Al2O3三元相图中的演变行为。研究发现,在该厂现行工艺条件下,LF喂钙处理可降低钢中的全氧含量和非金属显微夹杂含量。转炉炉后出钢至精炼出站全氧含量降低了27×10-6,非金属显微夹杂物含量减少了54.5%。稳态连铸坯中的氧、氮含量和显微夹杂含量较低。LF精炼喂钙线之前显微夹杂的主要成分为Al2O3。在LF精炼钙处理后,中间包及连铸坯中发现了大量的球形Ca O-Al2O3类夹杂,这表明钙处理效果良好,实现了将Al2O3夹杂物变性的目的。热力学计算结果表明钙处理过程中夹杂物的演变行为为Al2O3→Al2O3+CaO·6Al2O3+CaS→Al2O3+CaO·2Al2O3+Ca S（Ca S较多,Ca O较少）→Al2O3+CaO·2Al2O3+CaS（CaS较少,CaO较多）。

This study on the evolution behavior of the the Non-metallic inclusion in the steel was conducted systematically by the means of the oxygen and nitrogen analysis,microscopic inclusion statistics and SEMEDS energy spectrum.The CaS-CaO-Al2O3 tenary phase diagram in 1 600 ℃ was calculated and plotted by Factsage software.The evolution behavior of inclusions was analysed in the CaS-CaO-Al2O3 tenary phase diagram.It can be found that,under the current technological conditions,The total oxygen content and number of non-metallic inclusion in the molten steel has been decreased by the LF calcium wire-feeding treatment process.From the end of metal tapping to the tundish of caster,the total oxygen content has been decreased by 27×10-6.The number of non-metallic inclusion has been decreased by 54.5%.The content of the total oxygen and nitrogen and the number of the non-metallic inclusion in the steady billet is low.The main components of microscopic inclusion is Al2O3 before the calcium treatment in the LF.There are a great number of the globular CaO-Al2O3 inclusion observed in the sample after the calcium treatment,in the LF and in the Tundish and slab.This research results indicates that calcium treatment achieves good results and the objective of the modifing alumina inclusion has been achieved.The thermodynamic calculation results show that the evolution behavior of inclusion is as follows:Al2O3→Al2O3+CaO·6 Al2O3+CaS→Al2O3+CaO·2 Al2O3+CaS（higher CaS and less CaO）→Al2O3+Ca O·2 Al2O3+CaS（less CaS,higher CaO）.