Propagation of surface initiated rolling contact fatigue cracks in bearing steel

Rycerz, Pawel; Olver, A.D.; Kadiric, Amir

doi:10.1016/j.ijfatigue.2016.12.004

Cited by 135 publications

(58 citation statements)

References 36 publications

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“…The model is based on stress history and damage accumulation parameters and therefore considers only crack initiation. Fatigue cracks, such as those in micropitting, also have a propagation phase, and the relative length in time of these two phases is affected by the imposed conditions [34]. In particular, crack propagation is strongly affected by the direction of sliding: negative sliding (cracked surface slower) i.e.…”

Section: Discussionmentioning

confidence: 99%

Prediction of micropitting damage in gear teeth contacts considering the concurrent effects of surface fatigue and mild wear

Morales-Espejel

Rycerz

Kadiric

2018

Wear

135

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A B S T R A C TThe present paper studies the occurrence of micropitting damage in gear teeth contacts. An existing general micropitting model, which accounts for mixed lubrication conditions, stress history, and fatigue damage accumulation, is adapted here to deal with transient contact conditions that exist during meshing of gear teeth. The model considers the concurrent effects of surface fatigue and mild wear on the evolution of tooth surface roughness and therefore captures the complexities of damage accumulation on tooth flanks in a more realistic manner than hitherto possible. Applicability of the model to gear contact conditions is first confirmed by comparing its predictions to relevant experiments carried out on a triple-disc contact fatigue rig. Application of the model to a pair of meshing spur gears shows that under low specific oil film thickness conditions, the continuous competition between surface fatigue and mild wear determines the overall level as well as the distribution of micropitting damage along the tooth flanks. The outcome of this competition in terms of the final damage level is dependent on contact sliding speed, pressure and specific film thickness. In general, with no surface wear, micropitting damage increases with decreasing film thickness as may be expected, but when some wear is present micropitting damage may reduce as film thickness is lowered to the point where wear takes over and removes the asperity peaks and hence reduces asperity interactions. Similarly, when wear is negligible, increased sliding can increase the level of micropitting by increasing the number of asperity stress cycles, but when wear is present, an increase in sliding may lead to a reduction in micropitting due to faster removal of asperity peaks. The results suggest that an ideal situation in terms of surface damage prevention is that in which some mild wear at the start of gear pair operation adequately wears-in the tooth surfaces, thus reducing subsequent micropitting, followed by zero or negligible wear for the rest of the gear pair life. The complexities of the interaction between the contact conditions, wear and surface fatigue, as evident in the present results, mean that a full treatment of gear micropitting requires a numerical model along the lines of that applied here, and that use of overly simplified criteria may lead to misleading predictions.

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Section: Discussionmentioning

confidence: 99%

Prediction of micropitting damage in gear teeth contacts considering the concurrent effects of surface fatigue and mild wear

Morales-Espejel

Rycerz

Kadiric

2018

Wear

135

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“…Typical patterns of crack propagation across the surface are illustrated by the SEM images, as shown in Figure C to E. It can be seen that crack growth prefers to the frictional force direction. Pawel found that visible cracks have an initial angle of inclination to the surface of 20° to 30° in bearing steel. Deng noticed that the crack propagation could be divided into two phases: First, the crack propagates obliquely downward from the bearing raceway surface with an approximate inclination angle of 30° relative to the raceway surface.…”

Section: Resultsmentioning

confidence: 99%

“…Here, we focus on the second cracks, as seen in Figure A to C. Secondary cracks are observed to branch off the main crack and grow towards the surface, eventually liberating a fragment of the material and creating a pit formation . The secondary crack propagates into the prior austenite grain in Figures D and C but along the prior austenite grain in Figure E.…”

Section: Resultsmentioning

confidence: 99%

Statistical analysis on rolling contact fatigue in railroad axle bearing steel

Guo

Yang

et al. 2018

Fatigue Fract Eng Mat Struct

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High‐strength steels are widely used in high‐performance bearings utilized in most mechanical systems. However, there has been little statistical analysis regarding the fatigue failure behaviour of the material, where surface peeling resulted from contact fatigue during rolling is a significant life‐limiting mechanism. In this study, we examine the statistical behaviour of surface‐crack nucleation, propagation, and peeling in a high‐speed train axle bearing made of GCr15 steel by using a laboratory rolling‐contact equipment. We reveal that cyclic rolling‐contact leads to the formation of a hardness gradient in the outer ring of the bearing. The gradient layer is of several millimetres. The peeling rate could be as high as 28 μm per million cycles when the contact pressure is close to that applied in real service. Peeling‐induced cracking is dominantly transgranular. The incipient angle is about 23.2°, and its depth could be hundreds of micrometres. The findings reported here could be employed to assess the lifetime of bearings made of GCr15 steel and possible other engineering metals.

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“…Fig.7(c) shows the enlargement of the rectangular region 2, the surface cracks were visible, the length of them is about 10-25μm. These areas continue to expand and fall off to form spalling pits and wear debirs [16]. Fig.8 shows the plastic deformation layer thickness changes with the banded carbide grade.…”

Section: Rcf Failure Observations and Mechanism Analysismentioning

confidence: 99%

Effect of banded carbide structure on the rolling contact fatigue of GCr15 bearing steel

Li¹,

Zhang²

2017

Proceedings of the 2017 5th International Conference on Mechatronics, Materials, Chemistry and Computer Engineering (ICMMCCE 20

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In this paper, the influence of banded carbide structure on Rolling Contact Fatigue (RCF) of GCr15 bearing steel was investigated by using MMS-2A double-roller wear tester under dry friction at room temperature. Surface damage was characterized using SEM and OM. The results showed that with the increase of banded carbide grade, wear rate and friction coefficient were obviously increased and contact fatigue performance was deteriorated. For the high grade of banded carbide, the main failure form is fatigue pits and surface cracks. On the contrary, for the low grade of banded carbide, the main failure form is flaking off. Besides, with the increment of banded carbide grade, the thickness of plastic deformation layer increase. The fatigue cracks easy propagated in the plastic deformation layer along the rolling direction. Therefore, by reducing the banded carbide grade can effectively improve the rolling contact fatigue properties of bearing steel. Key words: GCr15 bearing steel; banded carbide; RCF 1.IntroductionBearing balls and rolling-element bearings experience subsurface initiated fatigue failures due to RCF.The bearings used in practical applications are designed to operate at nominal stress levels well below the yield strengths of the materials. However, the presence of imperfections and non-metallic inclusions introduces heterogeneity at the microstructural level [1].With increasing in number of cycles, the ratcheting strain accrues, and therefore it can serve as a meaningful parameter to quantify the evolution of a material damage due to RCF [2,3].Once this damage reaches a critical value, a fatigue crack nucleates in the subsurface of a material. Since this local plastic strain accumulation takes place in the vicinity of carbides, it is important to understand their role towards ratcheting under RCF loading conditions. Generally, the influence factors of RCF failure of bearing steel is non-metallic inclusion, distribution of carbide and purity of steel. Undoubtedly, previous studies have showed the RCF would reduce the life and reliability of many useful components, such as gears, rolling bearings [4][5][6]. Nagao M find the stiffness of an inclusion and its location have a significant effect on the RCF life, stiffer inclusions and inclusions located at the depth of maximum shear stress reversal are more detrimental to the RCF life [7].T.Karsch studied the effects of hydrogen content and microstructure on fatigue behavior of steel GCr15 in the VHCF regime [8],and it is found that increased hydrogen content in bearing steel at 5 ppm (by weight) will significantly promote bearing spalling failure [9,10]. Shigeo shmizu's studies show that the bearing fatigue life is directly related to the instantaneous contact time, with the increase of the instantaneous contact time, the fatigue life is also increased [11]. O.P.Datsyshyn introduced the mechanism of fatigue crack propagation in metallic materials [12]. G.John put forward the using of bearing steel under normal conditions, due

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Propagation of surface initiated rolling contact fatigue cracks in bearing steel

Cited by 135 publications

References 36 publications

Prediction of micropitting damage in gear teeth contacts considering the concurrent effects of surface fatigue and mild wear

Prediction of micropitting damage in gear teeth contacts considering the concurrent effects of surface fatigue and mild wear

Statistical analysis on rolling contact fatigue in railroad axle bearing steel

Effect of banded carbide structure on the rolling contact fatigue of GCr15 bearing steel

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