Low temperature plasma ion nitriding (PIN) of Inconel 690 alloy

Abstract

In this study an effort has been made for the plasma ion nitriding (PIN) of Inconel 690 alloy at low temperatures. After plasma ion nitriding, samples were characterized by various characterization techniques such as; scanning electron microscope with energy dispersive x-ray (SEM-EDX), x-ray diffraction (XRD) analysis, micro-hardness measurement and wear test by pin on disk technique for their microstructure study, phase study, growth kinetics of nitrided layer formation and to study wear properties. It was found that, surface micro-hardness increases after PIN process. A mix peak of epsilon (ε) phase with fcc (γ) phase was detected for all temperature range (350 °C to 450 °C), while the chromium nitride (CrN) phase was detected at elevated temperature range ∼450 °C. The calculated values of diffusion coefficient and activation energy for diffusion of nitrogen are in accordance with the literature. Volume loss and wear rate of the plasma nitrided samples decreases, but it increases as PIN process temperature increases.