LAUSR

Abstract This study investigated the relationship between the chemical reaction film formation derived from engine oil additives and crystal grain structure of a steel surface. Variations in the contact area between a rotating sapphire disc and a stationary steel pin were captured by a monochromatic high-speed camera. A fully formulated low viscosity engine oil was used as the lubricant. After friction tests, the elements on the surface were analysed using energy dispersive X-ray spectroscopy and the crystal grain structure of the top surface layer by electron backscatter diffraction. In-situ and ex-situ analyses revealed that plastic flow changed the crystal grain structure of the surface, inhibiting the formation of the chemical reaction film derived from additives.