Lubricated seizure of stainless steel observed by X-ray imaging

Lubricated sliding and seizure of stainless steel is of considerable interest in light of the better properties as it provides improved corrosion resistance, compared to conventional steels. The effect of stainless steel on oil stability during sliding is of importance as it contributes to the wear behaviour of the system. We have used an X-ray microscope for in situ observation of frictional seizure, wear and interfacial features during the testing of stainless steel specimens sliding against Al 6061 disk. This technique enables the observation of interfacial features at the hidden surfaces. Seizure tests were conducted at sliding speeds of 2, 4 and 5 m/s under lubricated conditions with plain mineral oil. The images obtained during the tests indicated a possible degradation of the lubricating oil, resulting in darkening at isolated locations as sliding continued. An increase in the shear rate (sliding speed) resulted in faster degradation of the oil and hence greater susceptibility to early seizure.