Tribological studies of plasma source ion nitrided low alloy tool steel

Abstract

Plasma source ion nitriding has emerged as a low-temperature, low-pressure nitriding approach for implanting nitrogen ions and then diffusing into metallic materials. In this work, an attempt has been made to develop a method for hardening 9SiCr low alloy tool steel at a process temperature of 250 °C by plasma source ion nitriding. The nitrided samples were characterized using optical microscopy, Auger electron spectroscopy, electron probe microanalysis and glancing angle X-ray diffraction. The wear tests were performed on a crank/connecting rod reciprocating tribometer. The dominant wear mechanisms were identified by the worn surface morphologies using scanning electron microscopy. The results indicate that the nitrided surface layers possess the improved abrasive wear resistance and increase the transition load from mild to severe wear, compared with the unnitrided samples. The formations of nitrides and nitrogen-containing solid solution are considered as the main reasons for improved tribological properties.