Inclination of Principal Residual Stress and the Direction of Cracking in Contact-Fatigued Ball Bearing Steel

1979 ◽  
Vol 23 ◽  
pp. 341-348
Author(s):  
Kikuo Maeda ◽  
Noriyuki Tsushima ◽  
Masatoshi Tokuda ◽  
Hiroshi Muro
Keyword(s):  
Residual Stress ◽  
Ball Bearing ◽  
Roller Bearing ◽  
High Hardness ◽  
Bearing Steel ◽  
Rolling Contact ◽  
Lubricating Oil ◽  
Peeling Test ◽  
Surface Fatigue ◽  
Ball Bearing Steel

Peeling is a surface fatigue failure of a roller bearing that consists of many shallow pits less than 10 pm in depth and cracks that link the pits. Peeling occurs rather easily on a smooth Surface when in contact with a rough surface under insufficient thickness of the lubricating oil film.X-ray residual stress measurements on and under the contact surface after a peeling test revealed that the 2θ versus sin2ψ curve is not linear and that it curves depending upon the rolling contact condition and especially upon the existence of slip. Nonlinearity of the 2θ-sin2ψ) curve has been reported by Wakabayashi in a study of residual stress accompanying the grinding of soft steel and by Faninger in a study of residual stress due to rolling contact with annealed steel, but hot in the case of high hardness steel such as ball bearing steel. No complete explanation of this non-linearity has been made as yet.

Fracture Surface Analysis of Ball Bearing Steel by X-Ray Residual Stress Measurement

1979 ◽  
Vol 23 ◽  
pp. 317-323
Author(s):  
Hirokazu Nakashima ◽  
Noriyuki Tsushima ◽  
Hiroshi Muro
Keyword(s):  
Residual Stress ◽  
Plastic Deformation ◽  
Fracture Surface ◽  
Ball Bearing ◽  
High Hardness ◽  
Bearing Steel ◽  
Plastic Deformation Zone ◽  
Static Fatigue ◽  
X Ray ◽  
Ball Bearing Steel

Plastic deformation necessarily accompanies fracture even in high hardness steels such as ball bearing steel, though it is within a very shallow layer just under the fracture surface. The depth of the plastic deformation zone can he determined by X-ray measurement of half value breadth. However, in the case of high hardness steel, the half value breadth is not changed significantly by this kind of plastic deformation. On the contrary, residual stress on the fractured surface was found to change remarkably depending on the mode of fracture such as static, fatigue or delayed types.

Tribological characterization of potential crankshaft bearing steels for roller bearing engines

2020 ◽  
pp. 135065012095778
Author(s):  
Aleks Vrček ◽  
Tobias Hultqvist ◽  
Tomas Johannesson ◽  
Pär Marklund ◽  
Roland Larsson
Keyword(s):  
Residual Stress ◽  
Combustion Engine ◽  
Roller Bearing ◽  
Surface Hardness ◽  
Bearing Steel ◽  
Engine Oil ◽  
Limiting Factor ◽  
Surface Fatigue ◽  
Bearing Steels ◽  
Wear Damage

A crankshaft roller bearing internal combustion engine (ICE) offers a five percent or more improvement in overall engine efficiency and, thereby, a reduction in a five percent of CO2 emissions, compared to a plain bearing supported crankshaft. Current forged crankshaft steels represent the limiting factor of the rolling component, therefore, a replacement of the crankshaft steel is required. Apart from this, the tribology of the rolling contacts has been shown to be detrimental when lubricated with current engine oils. Therefore, this paper investigates the tribological performance of potential crankshaft bearing steels, i.e. DIN C56E2 (G55); DIN 50CrMo4 (G50); and DIN 100Cr6 (G3), while utilizing a state-of-the-art low viscosity 0W20 engine oil and under conditions prevalent to ICE. For this, damage mode investigation was performed in a disc-on-disc setup. Based on the results, wear damage of DIN 100Cr6 discs was shown to be dependent on the steel grade of which the counterpart disc was made from and surface hardness difference between both discs. In addition, surface fatigue and wear damage can be completely eliminated by selecting a proper surface roughness and hardness combination. Also, while under an elevated roughness level, engine oil was shown to promote both surface fatigue and wear damage through the work of ZDDP additives, which under extreme conditions can act as an extreme pressure (EP) additive. The residual stress measurements using the XRD technique revealed relatively high compressive residual stresses for G55 and G50 in comparison to G3 steel after surface induction hardening. In addition, no significant changes in residual stress for G55 and G50 were observed after the test. In contrast, relatively high tensile stress was observed for G3 near the surface region. This suggests that the most commonly used 100Cr6 bearing steel, in this case, is the most susceptible to surface fatigue.

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