| With the rapid developing requirement for good quality steel,how rare earth element function in steel was focused by more and more researchers.Consequently,a good understanding of the function mechanism of rare earth in steel will help us to control the performance of steel and optimize the quality of steel.The study of phase equilibrium and thermodynamic property of the rare earth elements in the iron-based solution is the very important for steel research,exploiting and application.Before 1980's ago,the data was not accurate,because some investigators used the gross of the rare earth elements to take place of the dissolution content and activity of the rare earth element in the steel.Since 1980's,although some investigators improved the study methods,the area,depth and results of these research were still different.So the analysis of these representative results are meaningful.The mutual action between the light,heavy rare earth elements(such as Ce,Y,La,Nd) and important nonmetal elements(S,O,C,N) is summarized.A series of the reaction equilibrium principles and thermodynamic properties of the rare earth at the temperature of the steel smelting are described were bring forward.The effect of physical-chemistry and the mutual action mechanism were given.The deoxidation, desulfurization and both deoxidation-desulfurization of the rare earth in the steel are summarized and analyzed emphatically.The simple thermodynamic model is put forward for deoxidation and desulfurization.The rates of deoxidation and desulfufization are calculated and analyzed for different rare earth elements.The calculated results show that deoxidation ability from strong to weak is Ce＞Nd＞Y,desulfurization ability from strong to weak is La＞Ce＞Y.The trend and reasons for the rates of deoxidation and desulfurization of RE with variational original concentration of oxygen and sulfur in the molten iron were analyzed.The results are in accordance with thermodynamic calculate and experiment by other scientists. |
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