Fretting Wear of a Bearing Steel in Hydrogen Gas Environment Containing a Trace of Water

Abstract

Fretting wear tests on a bearing steel under gross slip condition were conducted in hydrogen and nitrogen gas environments containing water at 2 to 70 ppm using a new gas-tight chamber. Wear in hydrogen and nitrogen is sensitive to the water content of the gases and it increases as the water content increases. Water in these environmental gases reduces the coefficient of friction during the early cycles of experiments. Furthermore, exposure of the test specimens to high pressure hydrogen (40 MPa, 373 K, 200 hours) before the experiments enhances wear. These findings are consistent with the findings obtained in the authors' previous study, wherein the water content should have been higher and a comparison between hydrogen and nitrogen was not carried out because of insufficient control of water content. In this paper it is shown that wear in hydrogen is slightly larger than in nitrogen.