TRIBOLOGICAL BEHAVIOUR OF NITRIDED AND NITROCARBURIZED CARBON STEEL USED TO PRODUCE ENGINE PARTS

A. CABO; SONIA BRÜHL; G. PRIETO; W. TUCKART

INDUSTRIAL LUBRICATION AND TRIBOLOGY

EMERALD GROUP PUBLISHING LIMITED

Año: 2016 vol. 68 p. 125 - 133

0036-8792

Camshaftsare a relevant part of diesel engines that works under torsion, fatigue andwear efforts. They are usually manufactured by casting, forging or machiningfrom forged bar of low alloy steels and in most cases, the machined surfacesare quenched and tempered by induction heating. After that and in order towithstand the efforts imposed on the active surfaces and improve tribologicaland fatigue properties, the industry has been using thermochemical processes, suchas salt baths or gaseous nitriding and nitrocarburizing, for decades.This present work studied the effects of plasmanitriding and plasma nitrocarburizing, on the tribological behavior of thesteel SAE 1045HM3 proposed for camshaft manufacturing. After the plasmatreatments, the change in surface roughness was measured; the modified layers werestudied by X-rays diffraction and its thickness by optical microscopy. Thediffusion zone was evaluated by Vickers microhardness determinations, whiletribological behaviour was evaluated by means of pin-on-disk tests. Resultsshowed that plasma nitrided samples presented the best tribological behaviourcompared to the nitrocarburized ones. In addition, the influence of theroughness produced by the thermochemical processes also proved to be criticalfor the tribological performance of the samples.