Bearing steel quality and bearing performance

Trojahn, W.; Valentin, P.

doi:10.1179/1743284711y.0000000047

Cited by 15 publications

(10 citation statements)

References 3 publications

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“…70 to 350 µm were measured using confocal microscopy on various testing samples, which correlates well with the depth of the shear stress maximum. In Figure 4(a) the distribution and values of the shear stress using the FEM analyses of the BoR test is shown, whereas the shape of the WEA in a radial cross-section after Nital etching can be observed in Figure 4 , in (c) 10 6 and in (d) 1.910 8 . It was observed, that after 10 4 overrollings no WEA can be identified and the hardness remains constant at about 850 HV0.05, which is the initial hardness.…”

Section: Resultsmentioning

confidence: 99%

“…It is a high-alloyed, secondary-hardening steel which comprises a martensitic matrix with vanadium-rich MC and molybdenum-rich M2C carbides [1,6]. By using vacuum melting and remelting technology (VIM-VAR) in the production, the amount of non-metallic inclusions, gases and tramp elements is reduced and hence the lifetime increased [4,7,8] Due to the overrolling and hence high cyclic loading during the operation of roller bearings changes in the microstructure develop. These alterations are dependent on the loading level and the operating time and become visible in the light microscope after etching because of different contrasts.…”

Section: Introductionmentioning

confidence: 99%

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Investigation into microstructural changes due to the rolling contact fatigue of the AISI M50 bearing steel

Pritz

Marsoner

Ebner

et al. 2015

Surface and Contact Mechanics Including Tribology XII

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Roller bearings in aircraft turbines are commonly made of AISI M50 steel, because enhanced heat stability as well as highest reliability is required for this application. With a chemical composition of approximately 0.8 C, 4.0 Cr, 4.5 Mo, 1.0 V (all in wt.%) and using a specific vacuum melting and remelting technology for highest cleanliness M50 provides the best properties for such application. Despite some studies on this steel, there is still a lack of information on microstructural evolution during rolling contact fatigue (RCF). Hence, in order to get a better understanding of the microstructural evolution and as a consequence of the crack initiation, in the framework of this study a comprehensive set of experimental techniques were combined. For the RCF loading a so called ball-on-rod test was used. Microstructural alterations were analysed by various methods including optical light microscopy, confocal microscopy, scanning electron microscopy (SEM) with cross-sectional cutting by focussed ion beam (FIB), transmission electron microscopy (TEM) and microhardness measurements. Testing methods showed the build-up of a so-called white etching area (WEA) in a certain region below the raceway and the formation of butterfly-wings (BW) with micro-cracks at local microstructural inhomogeneity. Furthermore, all tested samples showed BW's which initiated on carbides, often with micro-cracks near the boundary to the matrix.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Investigation into microstructural changes due to the rolling contact fatigue of the AISI M50 bearing steel

Pritz

Marsoner

Ebner

et al. 2015

Surface and Contact Mechanics Including Tribology XII

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“…So, just two main atomic types including Fe and C elements are considered for the atomic model. The typical components of bearing steels consist of tempered martensite, homogeneously distributed primary spheroidized carbide, tempered carbide and retained austenite [24,25]. Among them, martensite is a supersaturated solid solution formed by the solubilization of carbon in α-Fe matrix [26].…”

Section: Introductionmentioning

confidence: 99%

Micromechanism of Plastic Accumulation and Damage Initiation in Bearing Steels under Cyclic Shear Deformation: A Molecular Dynamics Study

2022

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Fatigue failure usually occurs on the subsurface in rolling bearings due to multiaxial and non-proportional fatigue loadings between rolling elements. One of the main stress components is the alternating shear stress. This paper focuses on the micromechanism of plastic accumulation and damage initiation in bearing steels under cyclic shear deformation. The distribution of subsurface shear stress in bearings was firstly investigated by finite element simulation. An atomic model containing bcc-Fe and cementite phases was built by molecular dynamics (MD). Shear stress–strain characteristics were discussed to explore the mechanical properties of the atomic model. Ten alternating shear cycles were designed to explore the mechanism of cyclic plastic accumulation and damage initiation. Shear stress responses and evolutions of dislocaitons, defect meshes and high-strain atoms were discussed. The results show that cyclic softening occurs when the model is in the plastic stage. Severe cyclic shear deformation can accelerate plastic accumulation and result in an earlier shear slip of the cementite phase than that under monotonic shear deformation, which might be the initiation of microscopic damage in bearing steels.

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“…For example, the routine technologies available for the production of experimental cannot achieve oxygen concentrations of 6 wt-ppm, values routinely possible in industry. The paper by Trojahn 12 is particularly interesting in that it demonstrates that a cheap steel with a low oxygen concentration will not perform as well in a bearing application as one made using best practice but with the same oxygen content. This is because effort must be expended to ensure that the large inclusions which determine bearing life are kept to a minimum.…”

Section: Bearing Steelsmentioning

confidence: 99%

Editorial

2012

Materials Science and Technology

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It is extraordinary that a steel bearing can survive stress pulses of 2 GPa some half a million times a minute, over the service life of an aero engine. Or that it can be expected to reliably support the stochastic loads created by the buffeting of sails on giant offshore windmills designed to rescue the world from carbon dioxide catastrophes and wars driven by the thirst for oil. Bearing steels are the unsung heros of most of the arduous technologies that improve the quality of ordinary life; for the person pulling the rickshaw in Kolkata to the farmers harvesting the vast bread baskets of the prairies.And yet, the vast majority of bearing steels have their origins in the dim and distant history of tool steels. Tool steels must obviously be hard but do not necessarily have to be tough. A bearing consists essentially of parallel rings with some form of rolling element (balls, cylinders) accommodating the relative motion of the inner and outer rings. It therefore needs to sustain periodic contact stresses as the rolling element traverses the substrates. These loads are mostly a combination of torsion and compression, so it is not surprising that Stribeck in 1901 considered the 1C-1?5Cr tool steel for bearing applications, and that this steel was adopted by Fichtel and Sachs in 1905 for manufacture. Naturally, as technology became ever more demanding, so did the adaptation of the original tool steels, with dramatic improvements in cleanliness which led to corresponding enhancements in rolling contact fatigue life.Developments in the aircraft industries led the demand for higher operating temperatures, and hence the adoption of secondary hardening tool steels for aero engine bearings, followed by the case hardening versions to enhance core toughness. We are fortunate to have been able to persuade Zaretsky, one of the pioneers of the subject, to contribute a historical perspective to this special issue. 1

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Bearing steel quality and bearing performance

Abstract: For pricing reasons the extent of metallurgical treatment often is questioned about its influence on bearing performance. In this paper steels with three different quality levels are compared with regards to cleanliness and fatigue resistance.

Cited by 15 publications

References 3 publications

Investigation into microstructural changes due to the rolling contact fatigue of the AISI M50 bearing steel

Investigation into microstructural changes due to the rolling contact fatigue of the AISI M50 bearing steel

Micromechanism of Plastic Accumulation and Damage Initiation in Bearing Steels under Cyclic Shear Deformation: A Molecular Dynamics Study

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