低碳钢碳氮析出物的热力学计算

Thermodynamic model for carbonitride precipitation in low carbon steels

钢中的碳氮析出物通过细晶强化和析出强化方式对钢的力学性能有非常重要的作用.基于规则溶液的双亚点阵模型(其中一个为金属亚点阵,另一个为间隙原子亚点阵)建立了碳氮化钛、氮化铝以及硫化锰的热力学计算模型用以研究析出物的析出开始温度、给定温度的奥氏体成分,并将这一结果应用于CSP过程.经计算得Ti(CxN1-x),MnS和AlN的析出温度分别是1200℃,1440℃和1010℃,最大的体积分数分别为2·315×10-5,4·18×10-4和3·1×10-4.对比发现热力学的计算结果与Thermo-Calc的计算结果和有关文献的实验数据有较好的一致性.

Carbonitride precipitates have significant effects on the mechanical properties of steels via grain refinement and precipitation hardening. Based on the two-sublattice model （metal atom sublattice and interstitial atom sublattice） of regular solution, a thermodynamic model for the precipitates of titanium carbonitride, aluminium nitride and manganese sulfide was established to study the starting-temperature of precipitates and the austenite composition at a given temperature in a low carbon steel and applied to compact strip production （CSP for short） process. The calculation results show that starting-temperature of the precipitation of Ti（CxN1-x）, MnS and AIN are 1200℃ , 1 440 ℃ and 1 010℃, their mole fraction are 2.315 × 10^-5, 4.18 ×10^-4 and 3.1 × 10^-4, respectively. By comparison the simulation results of the model are in agreement with the calculated ones by the Thermo-Calc software and the available experimental data from some publications. The thermodynamic model can be a useful tool in studying the precipitates of low carbon steels and in analyzing the CSP process.