电渣重熔过程中渣成分变化及钢中氧含量预测

利用XRF和XRD技术分析了电渣重熔过程中不同时间所取渣样的化学成分和物相结构。XRF分析得到电渣重熔过程中渣中Al2O3、CaF2、CaO、SiO2、FeO等成分含量随熔炼时间的动态变化。XRD分析表明:凝固的渣中存在11CaO·7Al2O3·CaF2、12CaO·7Al2O3、CaSiO3等高熔点物质,导致炉渣性质发生变化。根据熔渣化学成分,参考CaF2-CaO-Al2O3渣系的等电导率图和等黏度图,得到了电渣的比电阻和黏度随冶炼时间的变化情况。采用炉渣结构共存理论建立了温度为1 923和1 973K时与渣中Al2O3平衡的钢液中Al]-O]平衡关系图。计算结果显示,针对实验研究的钢种,当钢中酸溶铝含量wAl]s在0.000 1%~1%范围内时,钢液中溶解氧含量随着wAl]s的增加先减小后增大,当钢中wAl]s达到0.25%时,钢液中wO]最小。在实验条件下,因渣成分变化导致的钢中wO]的波动范围是0.25×10-6~0.48×10-6。

Change of slag composition during electroslag remelting process and prediction of the dissolved oxygen content in steel

The composition and structure of electroslag sample at different time during electroslag remelting process were measured by using XRF and XRD methods. Changes of contents of Al2O3, CaF2, CaO, SiO2 and FeO with smelting time during electroslag remelting process were analyzed by XRF. Some phases with high melting temperature such as 11CaO??7Al2O3??CaF2, 12CaO??7Al2O3 and CaSiO3 were confirmed by XRD in solidified slag which led to the change of composition in the whole ESR process. The changes of conductivity and viscosity of slags with smelting time were analyzed based on the diagram of isothermal conductivity and viscosity in the CaF2-CaO-Al2O3 system. According to the composition of electroslag and the coexistence theory of slag structure, equilibrium relationship between dissolved aluminium and oxygen in liquid steel at 1923 and 1973K was established. The calculated result shows that, for the present experimental steel, when the content of dissolved aluminium in the molten steel is in the range of 0. 0001% to 1%, as dissolved aluminium increases, the content of dissolved oxygen in the molten steel firstly decreases and then increases, dissolved oxygen reaches the minimum when dissolved aluminium is 0. 25%.The variation range of dissolved oxygen in present experimental steel is 0. 25??10-6 to 0. 48??10-6 due to the slag composition change.