Finite Element Simulations of Geometric Distortions in Ferritic Nitrocarburized SAE 1010 Plain Carbon Steel

Nitrocarburizing is a case hardening process that is carried out in the ferritic temperature region of the Fe-C phase diagram. Although nitrocarburizing treatment improves the hardness and wear resistance it always results in geometric distortions. Machining or straightening the surface can eliminate the distortions but requires additional work hours and cost. Torque converter pistons and Navy C-rings specimens made from SAE 1010 plain carbon steel were used in the analysis. Navy C-rings are generally used for studying the dimensional changes of a material before analyzing the dimensional changes of the actual component. Navy C-rings of varying thickness were used to analyze the effect of distortions with thickness. Finite element simulations of Navy C-rings and torque converter pistons were developed to study the effect of nitrocarburizing process on distortions.  The distortion values from the simulations rely on the material properties of the compound layers. And the distortion predictions from the simulations, which are in agreement with the experimental values, are further used to tailor the ferritic nitrocarburizing treatment to reduce distortions.  Nitrogen and carbon concentration profile will be measured on the compound layers and the results will be incorporated in the model to optimize the heat treatment.