Anti-scuffing properties of ion sulfide layers on three hard steels

In order to improve the anti-scuffing properties of steels, a new low temperature ion sulfuration technology was utilized to modify the surfaces of high speed steel, die steel and plain carbon steel. Sulfide layers, dominated by FeS phase, were produced on the surfaces of the three steels. The anti-scuffing and tribological properties of the sulfide layers were investigated on a ball-on-disc friction and wear test rig of QP-100 model under oil lubrication. Scanning electron microscope (SEM) equipped with EDX and X-ray diffraction (XRD) were employed to analyze the morphologies of cross-section and scuffing surfaces of sulfide layers, as well as the surface phase structures. Scanning auger microprobe (SAM) and X-ray photoelectron spectroscope (XPS) were used to detect the element variation with depth and the valence states of boundary lubrication films of scuffing surfaces, respectively. The results showed that the anti-scuffing and tribological properties of all sulfurized steels were improved remarkably. The anti-scuffing and tribological properties decreased in the order of high speed steel—die steel—plain carbon steel. The difference in anti-scuffing and tribological properties of different steels was mainly determined by the hardness, microstructure and corrosion resistance of substrate.