Date of Award


Publication Type

Master Thesis

Degree Name



Mechanical, Automotive, and Materials Engineering

First Advisor

Derek O. Northwood

Second Advisor

Randy J. Bowers


Applied sciences




Nitrocarburizing is a thermochemical diffusion process that has been proposed as an alternative to carbonitriding to improve the surface characteristics of automotive components without producing unacceptable part distortion. In this study, gas, ion and vacuum ferritic nitrocarburizing using various heat treatment schedules were investigated and compared with a current carbonitriding procedure. Dimensional distortion and residual stresses in Navy C-Rings and torque converter pistons resulting from each treatment process were evaluated. The microstructure and microhardness, as well as the phase composition of the specimens, were also characterized.

The results of this study indicated that the nitrocarburizing process utilizing suitable heat treatment procedures gave rise to smaller size and shape variations in specimens than carbonitriding. However, given the tensile surface residual stresses induced by nitrocarburizing, additional wear testing needs to be carried out to confirm the possibility of replacing the current carbonitriding process with an appropriate ferritic nitrocarburizing procedure.