Investigation of Ferritic Nitrocarburizing by Computational Thermodynamics

Similar to the nitriding process [1], the state of the art for controlling the nitrocarburizing process is to measure and control the nitriding potential and carbon potential in the atmosphere in order to define the nitrogen/carbon concentration and phase stability at the steel surface. However, it is a big challenge to choose the right parameters including the nitriding potential and the carbon potential during the nitrocarburizing process. Extend our previous success of using computational thermodynamics to provide guidance on the nitriding process with the alloy specified Lehrer diagrams [2], the systematic investigation on the process parameters for the nitrocarburizing process is conducted. By using computational thermodynamics, a series of nitriding potential vs. carbon potential diagrams are developed for pure iron and alloy steels to predict the phase evolution during nitrocarburizing process. These diagrams are also helpful to understand the effect of alloy elements on the surface phase evolution during nitrocarburizing process. 1. Yang, M., et al., Simulation of the Ferritic Nitriding Process. International Heat Treatment and Surface Engineering, 2011. 5(3): p. 122-126. 2. Yang, M., et al., Modeling the gas nitriding process of low alloy steels. Journal of materials engineering and performance, 2013. 22(7): p. 1892-1898.