Microstructure-sensitive accumulation of plastic strain due to ratcheting in bearing steels subject to Rolling Contact Fatigue

Pandkar, Anup S.; Arakere, Nagaraj K.; Subhash, Ghatu

doi:10.1016/j.ijfatigue.2014.01.029

Cited by 78 publications

(38 citation statements)

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“…Due to their different mechanical properties compared to the metallic matrix, carbides act as stress concentrators; thus, a reduction in their size leads to a decrease in the stress concentration 34 , especially in the surroundings of a crack tip.…”

Section: Discussionmentioning

confidence: 99%

Influence of a cryogenic treatment on the fracture toughness of an AISI 420 martensitic stainless steel

Prieto¹,

Tuckart²,

Ipiña³

2017

Mater. Tehnol.

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Cryogenic treatments have been employed over the past three decades for both tool and high-alloy steels to improve their wear resistance, mainly through the transformation of retained austenite and the precipitation of fine carbides. However, as the enhancement of one material property is often at the expense of another, it is interesting to evaluate the effect of this type of treatments on the fracture toughness. The objective of the present work was to determine the plane-strain fracture toughness of a cryogenically treated low-carbon AISI 420 martensitic stainless steel by means of standardized fracture tests, performed in accordance with the ASTM E399 and ASTM E1820 standards. In this study, it was experimentally demonstrated that cryogenically treated specimens showed a simultaneous increase in the KIC and hardness of 30 % and 5 %, respectively, compared to conventionally treated specimens. Keywords: cryogenic treatment, carbide refinement, plane-strain fracture toughness, low-carbon martensitic stainless steel Obdelava s podhlajevanjem v zadnjih treh desetletjih, tako za orodja kot za visokolegirana jekla, pomeni izbolj{anje njihove odpornosti proti obrabi, predvsem zaradi preoblikovanja zadr`anega avstenita in zgo{~evanja finih delcev. Kakorkoli`e, izbolj{anje enega materiala je pogosto, vendar na ra~un drugega, zato je zanimivo oceniti u~inek takega tipa obdelave na lomnò ilavost. Predmet pri~ujo~ega dela je bila dolo~itev lomne`ilavosti kriogensko obdelanega nizkoogljikovega martenzitnega nerjave~ega jekla AISI 420, s pomo~jo standardiziranih testov zlomov, izvedenih v skladu s standardoma ASTM E399 in ASTM E1820. V {tudiji je bilo s poizkusi dokazano, da so kriogensko obdelani vzorci pokazali hkratno pove~anje KCI in trdote za 30 % in 5 %, v primerjavi s konvencionalno obdelanimi vzorci. Klju~ne besede: obdelava s podhlajevanjem, pre~i{~enje delcev, lomna`ilavost, nizkoogljo~no martenzitno nerjave~e jeklo

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Section: Discussionmentioning

confidence: 99%

Influence of a cryogenic treatment on the fracture toughness of an AISI 420 martensitic stainless steel

Prieto¹,

Tuckart²,

Ipiña³

2017

Mater. Tehnol.

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“…Before testing, the spring preloads were set to reach a maximum stress of 6.4 GPa in the Hertzian contact. This loading is around three times higher than the highest operational load in aircraft turbines during take-off, but necessary to reduce the testing time to acceptable values [1,11]. At a rotating speed of 2990 rpm the testing time for 10 8 overrollings is approx.…”

Section: Experimental Methodsmentioning

confidence: 95%

“…These microstructural inhomogeneities act as stress concentrators and lead to high local accumulation of plastification due to the cyclic loading. In addition, boundary surfaces may become detached, so local shear arises and micro-cracks can be initiated [4,10,11]. This alteration of the microstructure develops on two opposed sides of the inhomogeneity with a certain angle to the raceway dependent on the overrolling direction [1,4,10].…”

Section: Introductionmentioning

confidence: 99%

“…In this area around the inhomogeneity the martensitic matrix is transformed into a nano-crystalline structure eventually containing micro-cracks and partly debonded boundaries to inclusions. These micro-cracks can grow under ongoing loading and lead to instable crack growth and pitting [4,10,11]. This large dependence of the local microstructure in the highly stressed zone of up to some 100 microns below the raceway leads to the big spread in the life-time of bearings from the same batch [1,4].…”

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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“…Whilst there are various roller bearing failure mechanisms operating simultaneously, rolling contact fatigue (RCF) contributes substantially. RCF may occur in the subsurface, with many studies indicating cyclic subsurface shear stresses, combined with inherent defects, significantly contribute to damage in the static raceway [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

Mapping of axial plastic zone for roller bearing overloads using neutron transmission imaging

et al. 2018

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Article HIGHLIGHTS• A loading frame was designed to simulate bearing overloads on the ENGIN-X strain diffractometer at ISIS neutron source, UK.• Neutron transmission imaging was used to map a Bragg edge fitting parameter, associated with material yielding.• It was demonstrated that bearing overloads generate regions of subsurface plasticity in overloaded roller bearings.• Subsurface deformation, observed during roller bearing overload events, appears to reduce the bearings life expectancy. Premature failure of wind turbine gearbox bearings is an ongoing concern for industry, with sudden overload events potentially contributing towards raceway damage, significantly hindering performance. Subsurface stresses generated along a line contact cause material yielding, and a probable crack initiation site. Currently, the ability to study subsurface plastic zone evolution using non-destructive techniques is limited. Neutron Bragg edge imaging is a novel technique, allowing for two-dimensional mapping of the Bragg edge broadening parameter, indicative of bulk plastic deformation. An experiment on the ENGIN-X strain scanning instrument, at the ISIS neutron source, UK, was setup for Bragg edge transmission imaging, to measure the effect of in situ loading on the raceway of a bearing, scaled-down from a traditional wind turbine gearbox bearing. Results demonstrate a strong correlation between load and the Bragg edge width, and allow for future experimental development in studying, not only the effect of overloads on fatigue life, but also the use of neutron imaging for evaluating plastic deformation in engineering components. GRAPHICAL ABSTRACT abstract article info

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Microstructure-sensitive accumulation of plastic strain due to ratcheting in bearing steels subject to Rolling Contact Fatigue

Cited by 78 publications

References 38 publications

Influence of a cryogenic treatment on the fracture toughness of an AISI 420 martensitic stainless steel

Influence of a cryogenic treatment on the fracture toughness of an AISI 420 martensitic stainless steel

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

Mapping of axial plastic zone for roller bearing overloads using neutron transmission imaging

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