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

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ORIGINAL PAPER

In Situ Observation of Crystal Grain Orientation During Scuffing Process of Steel Surface Using Synchrotron X‑ray Diffraction K. Yagi1,2 · T. Izumi3 · J. Koyamachi4 · S. Sanda3 · S. Yamaguchi3 · K. Satio5 · M. Tohyama3 · J. Sugimura1,2 Received: 24 June 2020 / Accepted: 14 October 2020 © Springer Science+Business Media, LLC, part of Springer Nature 2020

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.

* K. Yagi [email protected]‑u.ac.jp 1



Department of Mechanical Engineering, Faculty of Engineering, Kyushu University, Fukuoka 819‑0395, Japan

2



International Institute for Carbon-Neutral Energy Research (I²CNER), Kyushu University, Fukuoka 819‑0395, Japan

3

Toyota Central R&D Labs., Inc., Nagakute 480‑1192, Japan

4

Department of Hydrogen Energy Systems, Graduate School of Engineering, Kyushu University, Fukuoka 819‑0395, Japan

5

Toyota Motor Corporation, Toyota 471‑8572, Japan





13

Vol.:(0123456789)

115  

Page 2 of 15

Tribology Letters

(2020) 68:115

Graphic Abstract

Keywords  Scuffing · In situ observation · Synchrotron · X-ray diffraction · Crystal grains · Orientation · Plastic flow · Phase transformation · Temperature

1 Introduction There is a growing interest in furthering our understanding of the scuffing phenomenon, which is a catastrophic failure of sliding contacts found in machine elements such as gears, cam-tappet systems, and journal sliding bearings. When scuffing occurs in a contact area, a significant increase in friction, temperature, vibrations and noise may cause notable damage to the mating surfaces. To prevent an occurrence of scuffing, a thin hydrodynamic film separates the mating surfaces and supports the load applied to the contact area. Even if direct contacts occur between surfaces owing to an insuffici