铁液洁净度对凝固热力学参数的影响

Dependence of Thermodynamic Parameters of Solidification on Liquid Iron Cleanness

为了给高洁净钢连铸细晶技术提供相关理论依据,在高温钼丝炉中通过对电解纯铁加金属铝和硅脱氧,获得不同铁液洁净度的试样。利用差热分析法测定了试样在相同冷却速度下的过冷度。利用凝固过程热力学理论研究了铁液洁净度与过冷度、凝固热力学驱动力、形核功和临界晶核半径等的关系。结果表明:随着铁液洁净度的提高,铁液凝固时的过冷度增大,形核所需的凝固热力学驱动力变大,非均质形核功和临界晶核半径减小。

The pure iron melt was deoxidized by metallic aluminium or silicon in a Mo wire resistance furnace and the specimens containing different oxide contents were obtained. The DTA method was employed to measure the undercooling of samples during solidification. The relationship between the cleanness of liquid iron and undercooling, thermodynamic driving force of nucleation, the activation energy to form a crystal nucleus and the critical radius of nucleus has been investigated in terms of thermodynamics in solidification. The results shows that with the increase of cleanness of liquid iron, the undercooling and thermodynamic driving force increase, while the heterogeneous activation energy and critical radius of nucleus decrease. A theoretical basis for the continuous casting technique of clean steel to obtain a fine grain structure was afforded.