A comparison of the performance of AISI 52100 and AISI 440C ball bearings in a corrosive environment

Abstract

The paper describes experiments to compare the performance of two ball-bearing steels in an unusual environment based on conditions in a power station application. The materials tested were the conventional AISI 52100 ball-bearing steel (which had been suffering from corrosion damage in the application) and an alternative material, the martensitic stainless steel AISI 440C. The test atmosphere was moist carbon dioxide at a pressure of about 3 MPa, and bearings were deliberately contaminated with a representative amount of sodium chloride. The objective of the tests was to compare the rolling-contact fatigue performance of the materials and to look for other failure mechanisms such as hydrogen embrittlement. Actual ball-bearing assemblies were used as test specimens. Failure rates were found to be between 1 and 2 orders of magnitude higher than would have been expected under ideal conditions, but in spite of various differences in morphology rolling-contact fatigue appeared to be the only significant failure mechanism. Results were analysed statistically by assuming that failures fitted an exponential distribution, and it was shown that the stainless bearings performed more than twice as well as those made from conventional steels.