高铁弹条钢夹杂物塑性化控制的热力学分析

提高高铁弹条钢的疲劳性能，除了要求弹条钢具有较高的纯净度外，还必须控制弹条钢中的非金属夹杂物。弹条钢中存在的脆性和不变形非金属夹杂物是弹条钢疲劳断裂的重要原因，所以必须控制弹条钢中的夹杂物为低熔点和具有良好的变形能力。借助Factsage热力学计算软件对1873K时钢液与夹杂物间的平衡进行了计算，确定了生成具有良好变形能力的低熔点CaO-SiO2-Al2O3系夹杂物所需要的钢液成分。结果表明：将夹杂物的成分控制在CaO-SiO2-Al2O3系的低熔点区域2中时，钢液中的溶解氧含量为（1～3）×10^-6，远远低于将夹杂物成分控制在低熔点区域1中时的溶解氧的含量，此时可以同时实现夹杂物塑性化和钢液纯净化的要求。

Thermodynamic Analysis of Control on Plasticization of Non-Metallic Inclusions in the Spring Steel of High-Speed Railway

To improve the fatigue property of spring steel used in high-speed railway, besides the requirement of high cleanliness of spring steel, the non-metallic inclusions are needed to be controlled. Brittle inclusions and point-like inclusions are the important reasons of fatigue fracture for spring steel. Therefore, it is essential to control the inclusions composition to the target of low melting point and good deformation capacity. Thermodynamic equilibrium between molten steel and inclusions at 1 873 K have been calculated by the themodynamic software Factsage in present study, and the appropriate steel composition corresponding to CaO-SiO2-Al2O3 system inclusions with good deformation capacity and low melting point has been determined. It is indicated that the dissolved oxygen content is estimated to be （ 1 - 3） × 10 ^-6 when the composition of inclusions is controlled in the second area of low melting point of CaO-SiO2-Al2O3. It is far lower than the dissolved oxygen content of the first area of the low melting point of CaO-SiO2-Al2O3 , and the aim of achieving plastic inclusions and clean spring steel can be realised too.