Due to their enhanced mechanical properties, gas carbonitrided steel components containing martensite and nitrogen stabilized austenite are currently widely used for highly loaded and severe application conditions. Carbon and nitrogen (C–N) concentration profiles developed during the gas carbonitriding have significant effect on the final properties of the steel. To achieve consistent properties and increase the reliability of processes, simulation of the C–N profile and evolving precipitates during the carbonitriding is essential. Generally, it is observed that the surface nitrogen content developed in the low-alloyed bearing-grade steels is much higher compared to the nitrogen potential in the furnace atmosphere during gas carbonitriding. The formation of nitrides/carbonitrides is one of main reasons for this difference. Thus, diffusion equations cannot be directly applied to calculate the C–N profile, as they do not include precipitation. To solve this problem, a mathematical approach is developed in this work. Thermodynamic data from MatCalc and experimental data are used to formulate equations to calculate the precipitated fraction of C–N during carbonitriding. Furthermore, these equations are integrated with diffusion equations to predict C–N profile that includes precipitates and the developed model is validated with experiments.

由于其增强的机械性能，含有马氏体和氮稳定的奥氏体的气体碳氮共渗钢部件目前广泛用于高负荷和严苛的应用条件。气体碳氮共渗过程中形成的碳和氮（C–N）浓度分布对钢的最终性能有重要影响。为了获得一致的性能并提高过程的可靠性，在碳氮共渗过程中模拟C–N曲线和析出的沉淀至关重要。通常，观察到，与气体碳氮共渗过程中炉气氛中的氮势相比，低合金轴承级钢产生的表面氮含量要高得多。氮化物/碳氮化物的形成是造成这种差异的主要原因之一。从而，扩散方程不能直接用于计算C–N剖面，因为它们不包括降水。为了解决这个问题，在这项工作中开发了一种数学方法。来自MatCalc的热力学数据和实验数据可用于公式化，以计算碳氮共渗过程中CN的沉淀分数。此外，这些方程式与扩散方程式集成在一起，可预测包括沉淀物的C–N剖面，并通过实验验证了开发的模型。