Y-S-O三维稳定相图及夹杂物形成机理

Three-dimensional stability diagram of Y-S-O and formation mechanism of inclusion

基于Fe-Y-S-O体系热力学数据,采用Matlab软件绘制了1 873 K温度下Y-S-O三维稳定相图,该相图可直观地反映元素变化规律和夹杂物析出顺序。结果表明,Fe-Y-S-O体系中含钇夹杂物主要包括Y_(2)O_(3)、Y_(2)O_(2)S、YS和Y_(2)S_(3)。常规炼钢工艺下Y_(2)S_(3)夹杂物较难形成,通常含钇夹杂物以Y_(2)O_(3)、Y_(2)O_(2)S和YS为主;当硫质量分数大于0.07%时,Y_(2)S_(3)夹杂物才能生成。稀土钇加入钢液后,首先形成Y_(2)O_(3)夹杂物,而后与硫反应生成Y_(2)O_(2)S夹杂物,最后形成YS夹杂物,随着氧质量分数的降低,含钇夹杂物转变路径为Y_(2)O_(3)→Y_(2)O_(2)S→YS。由于基础热力学数据对Y-S-O体系稳定相图影响较大,目前报道的稀土钇在钢中热力学数据的可靠性仍需探讨,一次和二次相互作用系数亟需补充和完善。

Based on the thermodynamics data of Fe-Y-S-O system, a three-dimensional stability diagram of Y-S-O at 1 873 K was established using the Matlab software, which could reflect the change of related elements and the precipitation order of inclusions directly. The result shows that main inclusions in Fe-Y-S-O system are Y_(2)O_(3),Y_(2)O_(2)S, YS and Y_(2)S_(3). Under the conventional steelmaking process, it is difficult to form Y_(2)S_(3), and the main Y-containing inclusions are Y_(2)O_(3),Y_(2)O_(2)S and YS. When S mass fraction is larger than 0.07%, Y_(2)O_(2)S inclusion can be formed. With the addition of rare earth Y to molten steel, YOinclusion is first formed and then transferred to Y_(2)O_(2)S, and YS inclusion is finally generated. With the decrease of oxygen content, the evolution route of Y-containing inclusions is Y_(2)O_(3)→Y_(2)O_(2)S→YS. The basic thermodynamic data has significant influences on the stability diagram of Y-S-O system, and the reliability of rare earth Y in reported thermodynamic data needs further discussion. The first and second order interaction coefficients of relevant elements need further supplementary and perfection.