Nb在铸铁中的物理冶金学作用原理

Physical-Metallurgical Effect Fundamentals of Niobium in Cast Iron

介绍了Nb在铁基合金中的存在形式,根据NbC和NbN在不同铁基合金中的溶度积公式,分析了Nb在铸铁中的存在形式。在此基础上,分析了Nb在铸铁中的作用机理。固溶Nb具有非常重要的调节共析相变及强化铁素体基体的作用,凝固过程析出的Nb(C,N)可显著提高耐磨性,在奥氏体温度区间晶界析出的Nb(C,N)能有效阻止晶粒长大,合适的成分设计和工艺措施可充分发挥Nb的作用效果。

The existing type of niobium in the matrix of cast irons was introduced.Based on the formulas of the solubility product for NbC and NbN in different iron matrixes,the existing types of niobium in the cast irons were analyzed.And on this base,the effect mechanism of niobium in the cast irons was analyzed.The solidly solved niobium had very important effect to modify the eutectoid transformation and to strengthen the ferrite matrix;the Nb（C,N） precipitating in solidification process could obviously increase wear resistance;the Nb（C,N） precipitating in the austenite temperature interval at the crystal boundaries could effectively retard the grains growth.Appropriate composition design and process measures could give full play to the effect of niobium.