In Situ Observation of Crystal Grain Orientation During Scuffing Process of Steel Surface Using Synchrotron X-ray Diffraction

Abstract

Scuffing is a catastrophic failure that causes significant surface damages such as plastic flow and welding with a marked increase in friction, wear, temperature and noise. In this study, variations in the crystal grain structure of a steel surface was analysed in situ during the scuffing process using a synchrotron X-ray diffraction system, combined with a visible camera and a near-infrared thermometer. The in situ observation system was synchronously operated to capture a contact area between a rotating sapphire ring and a stationary bearing steel pin. The Debye-Scherrer ring diffracted from the contact area was captured by a two-dimensional detector. The scuffing behaviour could be classified as either micro scuffing or macro scuffing. During the micro scuffing period, plastic flow occurred intermittently with a significant temperature rise of approximately 1000 °C. During the macro scuffing period, heat was continuously generated over the contact area. When plastic flow occurred, the captured Debye-Scherrer ring indicated the orientation of crystal grains as well as a phase transformation from martensite to austenite. This study constitutes the first in-situ observation of the behaviour of crystal grains in the dynamic recrystallisation process occurring during the scuffing process.

Quasi‐Single Crystalline Cuprous Oxide Wafers via Stress‐Assisted Thermal Oxidation for Optoelectronic Devices

“…The Debye–Scherer rings obtained by 2D‐XRD were conducted to further investigate the structure order of Cu 2 O samples and the mechanism, as illustrated in Figure S5, Supporting Information. [ 28,29 ] As shown in Figure 2c, the Debye rings of Cu 2 O prepared by the control methods have several bright spots or rings, indicating polycrystalline structure and/or disordered orientation. However, the concentrated bright spots indicate that the SSATO‐Cu 2 O and BSATO‐Cu 2 O crystals orient in perfect (110) diffraction.…”

A review of advances in tribology in 2020–2021

“…The subsurface microstructure of the tested SS samples changed greatly, and a thin nanocrystalline layer with transformed martensite was induced by severe plastic deformation undergone during the tests. Yagi et al [256] constructed an in-situ test rig (Fig. 25), which combined a synchrotron X-ray diffraction detector with a visible camera and a near-infrared thermometer, to observe the changes in crystal grain orientation, surface temperature, heated area, as well as friction coefficient.…”

In-Situ Observation of the Effect of the Tribofilm Growth on Scuffing in Rolling-Sliding Contact

“…Fig 6. The effect of load and duration of the running-in stage on friction coefficient in the subsequent 75 N test sequence.…”

“…For scuffing to occur, both the elastohydrodynamic (EHL) film and any protective tribofilms present on the surfaces must break down, resulting in direct metal-metal contact and adhesion [5,6]. The conditions that lead to the breakdown of EHL films have been quite extensively studied [7] and form the basis for several important predictive scuffing models based on critical temperature and related PV (load/sliding speed) criteria [8,9].…”

“…Bayat et al [16] suggested that, while parts of tribofilms were removed from surfaces after micro-scuffing, this did not propagate to catastrophic scuffing until a critical sliding speed was reached at which tribofilms could not form quickly enough on exposed surfaces. The term micro-scuffing refers to local scuffing that does not persist or spread over the whole surfaces and is characterised by a sudden rise and then quick fall of friction coefficient [6,15,[18][19][20]. As well as antiwear additives and EP additives, Ingram et al [17] showed that a long-chain amide type of friction modifier improved scuffing performance.…”