Analysis of the Tribological Behaviour of Stainless and Ball Bearing Steels Sliding in the Presence of Sulphur Extreme-Pressure Additives

Abstract

Conventional wear tests using a Four-Ball Lubricant Tester with the British Standard SAE 52100 steel were supplemented by tests with a stainless steel (AISI 420). Four combinations of these two materials were studied, namely each material was used in turn for the upper (driven) ball and the lower (clamped) balls. The tribological behaviour of stainless and ball bearing steel were studied under extreme pressure and/or anti-wear lubrication conditions in the presence of sulphur and sulphur containing additives, in order to compare the wear behaviour of the AISI 420 stainless steel with the SAE 52100 steel, taking into account the influence of chromium in both materials. Electron Probe Microanalysis and Glancing Angle X-ray Diffraction combined with Scanning Electron Microscopy have been used to identify the thin films produced on the worn surfaces and to study the micro- Structures of the subsurface layers. This investigation shows that the wear behaviour of a combination of materials is worsened by the greater use of the stainless steel in the rotating and stationary balls. The percentage of chromium does have a deleterious effect on the wear behaviour of the AISI 420 stainless steel, where the anti wear and extreme pressure actions were suppressed. These effects were 3 investigated using surface analytical techniques by using the same and mixed specimens.