A Study of Surface Damage at Low-Amplitude Slip

Abstract

The effect of extremely small slip amplitudes (0 to 5 μm) on transitions in the fretting process, such as initiation of surface damage, development of severe surface damage, microcrack initiation and the development of mild wear, was investigated. For SAE 52100 against SAE 52100 steel, the minimum slip amplitude associated with the onset of mild oxidation or surface staining was approximately 0.06 μm. Studies at higher amplitudes of motion indicated a transition from minimal surface damage to severe or significant damage at 2.8 μm. A further slight increase in amplitude to approximately 3.0 μm resulted in a transition into a regime characterized by fatigue crack formation. These transformations were found to be influenced to some extent by material composition and hardness. The onset of severe surface damage occurred at 1.1 μm for SAE 52100 against SAE 1018 and at 0.5 μm for a nickel chrome Hastelloy B alloy against SAE 1018 steel. In general, the amplitude of microslip characterizing the transition from extremely mild to severe surface damage was found to increase with increasing material hardness.