In Situ Observation of Heat Generation Behaviour on Steel Surface During Scuffing Process

Yasuo Matsuzaki,Joichi Sugimura,Kazuyuki Yagi

doi:10.1007/s11249-018-1095-x

Abstract

In the current study, the heat generation behaviour at plastic flow area in the contact area during a scuffing process was observed in situ using a monochrome high-speed camera that detected both visible and near-infrared light. The scuffing test was conducted using a pin-on-disc test rig comprising a rotating sapphire disc and a fixed martensitic steel pin. Engine oil was supplied as a lubricant. The images captured by the high-speed camera clearly showed changes in the contact area and the heat generation behaviour. It was found that the heat generation behaviour could be classified into three stages during scuffing. In the first stage, local heat generation occurred intermittently at local severe contact points, such as the passing of transfer layers on the sapphire disc and the trailing edge of the contact area. In the second stage, heat generation occurred intermittently over larger areas in which heat had been generated until that time. When the entire contact area had previously generated heat, heat generation became continuous throughout the contact area in the third stage. During the third stage, the contact area was increased rapidly, which caused catastrophic failure. These results highlight important questions regarding material phenomena that remain to be investigated.

Highlights

Scuffing is a catastrophic surface failure occurring at the contact areas between the sliding surfaces of machine parts operated under high sliding speeds and high loads, such as piston–cylinder pairs, journal bearings in crankshaft–connecting rod pairs, and gears
Heat experienced area expands to whole surface heat generaƟon occurs conƟnuously Fig. 20 Schematic of transition of heat generation behaviour leading to macroscale scuffing surface, thereby increasing friction
The feedback process based on the relationship between friction and temperature appears to contribute to the progress of scuffing

Summary

Introduction

Scuffing is a catastrophic surface failure occurring at the contact areas between the sliding surfaces of machine parts operated under high sliding speeds and high loads, such as piston–cylinder pairs, journal bearings in crankshaft–connecting rod pairs, and gears. SAE 0W-8 is available in the market [1] With these changes, lubricated areas are subjected to more severe conditions. Scuffing seems to be initiated by the breakdown of the protective films intended to prevent direct contact between mating surfaces. Based on the hydrodynamic lubrication theory, it has been proposed that as the friction surface temperature exceeds a critical temperature, the hydrodynamic fluid film breaks, resulting in scuffing [2,3,4,5,6,7]. It is suggested that oil starvation due to the agglomeration of wear particles can cause the breakdown of the fluid film, leading to scuffing [8, 9]. The magnitude and orientation of the surface roughness are key factors influencing for fluid film breakdown [15] and lubricant flow [16, 17].

Results

Discussion

Conclusion