含Nb细晶高强IF钢热变形行为的析出热力学

Precipitation Thermodynamics in Nb Contained Fine Grain and High Strength IF Steel during Hot Deformation

以新型含Nb细晶高强IF钢为研究对象,运用规则溶液亚点阵模型计算了实验钢从均热(1523K)冷却至室温(293K)的各个工艺过程中碳氮化物析出相的平衡体积分数、析出相的组成成分、各组元的平衡质量分数。计算结果表明,从均热到冷却至室温(1523K^293K)的过程中,随着温度的降低,固溶于基体中的Nb、C、N元素的质量分数逐渐减小,析出相平衡体积分数先增大后减小,NbN在析出相中比例逐渐降低,NbC在析出相中比例逐渐增加。至室温(293K)时,Nb和N元素几乎全部析出,碳氮化物不再继续析出。

For a new type of Nb fine grain high strength IF steel,the equilibrium volume fraction and composition of carbonitride precipitation as well as the mass fraction of each element from soaking(1523K)to room temperature(293K)were calculated by use of the regular solution sublattice model.The calculating results show that with decreasing temperature the mass fraction of Nb、C and N dissolved in matrix decreases,the equilibrium volume fraction of precipitation first increases and then decreases,the ratio of NbN in precipitates decreases and the ratio of NbC in precipitates increases. When cooling to room temperature(293K),Nb and N elements are completely precipitated,and no more precipitation for any longer.