Tribological Properties of Pulsed Ion Nitrided AISI 4140 Steel

摘要

The present study was conducted in order to investigate the tribological behavior of plasma nitrided AISI 4140 steel by using a DC pulsed glow discharge technique. Microstructure and structural characterizations were performed by using scanning electron microscopy (SEM) and X-ray diffraction (XRD) techniques. A compound layer with a thickness between 6 to 8 #mu#m containing #EPSILON# (Fe_3N) and to a lesser extent #gamma#' (Fe_4N) was identified. Wear tests were performed with a pin-on-disc configuration. The tests were carried out at room temperature in air by using two different pins materials (AISI 1086 and WC-6percentCo). A sliding speed of 0.1m.s~(-1), 5 N load and 700 m maximum sliding distance on both substrate and nitrided samples. The friction coefficients found for the different tribological pairs under study: tungsten carbide pin- plasma nitrided disc, AISI 1086 pin- plasma nitrided disc and AISI 1086 pin- AISI 4140 disc were between 0.34-0.6, 0.49-0.6 and 0.475-0.57, respectively. Wear volumes of 0.0453 mm~3, 0.0511 mm~3 and 0.00077 mm~3 have been determined for the tribological pairs mentioned above. The surface topography of the wear scars on both samples and pins have been determined by using scanning electron microscopy and by using 3D stylus profilometry.