Fatigue Life Performance of Hybrid Angular Contact Pyrowear 675 Bearings

Trivedi, Hitesh K.; Rosado, Lewis; Gerardi, David T.; Givan, Garry D.; McCoy, Bryan

doi:10.1520/stp160020170003

Cited by 14 publications

(10 citation statements)

References 26 publications

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“…In corrosive environments, the overall wear lifetime may be controlled by resistance to corrosion initiation, in which case LTT and CN could provide greater benefit than HTT. Previously conducted wear studies are in agreement with the recommendations given, and the results of this study provide nanoscale insight to help understand why HTT outperformed both CN and LTT during rolling contact fatigue testing even though it had significantly lower corrosion resistance [29,30]. Based on this work, P675 HTT would be recommended over the other two tempering procedures for use in aerospace bearings where corrosion is not a primary concern.…”

Section: Discussionsupporting

confidence: 82%

“…The nominal bulk composition of P675 (UNS S42670, the MSS studied here) prior to heat treatment is shown in Table 1 [29]. To increase surface hardness, P675 samples were carburized, followed by quenching and tempering, to harden the outer layer or case.…”

Section: Methodsmentioning

confidence: 99%

“…Samples differed in the final tempering temperature and carburization atmosphere: high-temperature tempering (HTT) at 496 °C, low-temperature tempering (LTT) at 315 °C, and carbo-nitrided (CN) where the case was obtained through a carburizing cycle followed by nitriding cycle during heat treating. Further details on the processing routes are discussed in previous works [9,10,29,30]. Prior to SPM characterization, samples were mechanically ground with SiC paper (to 2000 grit) in deionized (DI) water, followed by sequential polishing to 0.02 µm with a colloidal silica aqueous slurry.…”

Section: Methodsmentioning

confidence: 99%

“…Compared to M50, surface hardened P675 can be significantly more corrosion-resistant, and higher processing temperatures typically increased susceptibility to general corrosion damage, while lower temperatures exhibited more localized corrosion relative to untreated P675 [7]. The influence of processing on P675 wear performance for the same steels in non-corrosive wear testing has also been reported, where higher processing temperatures (HTT) yielded longer bearing lifetimes compared to low-temperature temper (LTT) [29,30]. However, there remains a need for research into the interdependency between simultaneously balancing corrosion resistance and surface hardness for bearing applications, since wear resistance (i.e., bearing performance) in corrosive environments is ultimately limited by corrosion [11].…”

Section: Introductionmentioning

confidence: 99%

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Corrosion Initiation and Propagation on Carburized Martensitic Stainless Steel Surfaces Studied via Advanced Scanning Probe Microscopy

et al. 2019

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Historically, high carbon steels have been used in mechanical applications because their high surface hardness contributes to excellent wear performance. However, in aggressive environments, current bearing steels exhibit insufficient corrosion resistance. Martensitic stainless steels are attractive for bearing applications due to their high corrosion resistance and ability to be surface hardened via carburizing heat treatments. Here three different carburizing heat treatments were applied to UNS S42670: a high-temperature temper (HTT), a low-temperature temper (LTT), and carbo-nitriding (CN). Magnetic force microscopy showed differences in magnetic domains between the matrix and carbides, while scanning Kelvin probe force microscopy (SKPFM) revealed a 90–200 mV Volta potential difference between the two phases. Corrosion progression was monitored on the nanoscale via SKPFM and in situ atomic force microscopy (AFM), revealing different corrosion modes among heat treatments that predicted bulk corrosion behavior in electrochemical testing. HTT outperforms LTT and CN in wear testing and thus is recommended for non-corrosive aerospace applications, whereas CN is recommended for corrosion-prone applications as it exhibits exceptional corrosion resistance. The results reported here support the use of scanning probe microscopy for predicting bulk corrosion behavior by measuring nanoscale surface differences in properties between carbides and the surrounding matrix.

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Section: Discussionsupporting

confidence: 82%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Corrosion Initiation and Propagation on Carburized Martensitic Stainless Steel Surfaces Studied via Advanced Scanning Probe Microscopy

et al. 2019

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“…The analytical life predictions with the above failure stress modifications are shown in Figure 2. Experimental life data for the 40-mm hybrid bearing obtained by Rosado et al, 19 along with more recent data published by Trivedi et al 28 are summarized in Table 3. In both these data sets, residual stress measurements are carried out on fresh races; thus, they are Type 1 residual stresses.…”

Section: Failure Stress Modification Due To Residual and Hoop Stressesmentioning

confidence: 99%

Failure stress modification in fatigue life models for rolling bearings

Gupta¹

2019

Proceedings of the Institution of Mechanical Engineers, Part J:

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The critical subsurface shear stress related to rolling contact fatigue is modified to model the effects of residual stress common in case hardened materials, such as M50-NiL. The role of hoop stress, generated due to race rotation and shrink fits, is also modeled. It is shown that even relatively low levels of compressive residual stress could contribute to notable increase in bearing life. An equivalent life modification factor is dependent on both residual stress and applied load. Model predictions are in agreement with available experimental life data obtained with a 40-mm angular contact ball bearing with M50-NiL races and silicon nitride balls. The stress modification approach is also applied to model the role of any fatigue limiting shear stress, such that the solutions converge to validated Lundberg–Palmgren solutions as limiting stress reduces to zero. However, bearing life predictions at light loads, under any reasonable limiting stress, are unreasonably high. As an alternate approach, the empirical constant in the limiting stress model, with a prescribed limiting stress, is determined by least-squared regression between model predictions and available experimental life data. With such an approach, the least-squared deviation between model predictions and experimental data shows a monotonic increase as a function of the limiting stress with a minimum at no limiting stress. This observation suggests that simple failure stress modification in the current subsurface stress-based models may not be suitable to implement any fatigue limiting stress for rolling contacts.

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Interaction of anti‐wear additiveTCPwith advanced bearing steels

Trivedi

Rosado

2022

Lubrication Science

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The quest for high‐performance energy efficient aircraft turbine engines has led to the development of a number of high‐performance rolling element bearing materials and engine lubricants with the aim of providing superior mechanical component durability. The heat treatments/surface treatments used to achieve the desired physical and mechanical properties for these newer alloys can result in altered surface chemistry from currently used materials. Surface chemistry plays an important role during lubricant‐bearing material interactions and the formation of beneficial tribological films during component operation. The objective of this study was to analyse the tribo‐films formed on bearing surfaces and investigate the interaction of lubricant additives, specifically the phosphorus‐based anti‐wear additive tricresyl phosphate (TCP), with different bearing materials under relevant bearing operating conditions. Bearing tests were conducted on 208‐size (40 mm bore) angular contact bearings at 127°C and 154°C using gas turbine engine lubricants conforming to MIL‐PRF‐23699G at maximum Hertzian contact stresses of 3.1 GPa and 3.55 GPa. Bearing materials evaluated included AISI M50, M50NiL, nitrided M50NiL (N) and three variants of Pyrowear 675 with silicon nitride rolling elements. Tribo‐films were analysed using Energy dispersive X‐ray spectroscopy and Auger Electron spectroscopy. Results indicate that phosphorus‐rich anti‐wear tribo‐films form on all of the bearing materials studied. The applied thrust load and heat treatment had a significant effect on tribo‐film thickness. The study also suggests that current gas turbine engine lubricants formulated with TCP should form beneficial tribo‐films that enhance bearing fatigue life and performance.

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Fatigue Life Performance of Hybrid Angular Contact Pyrowear 675 Bearings

Cited by 14 publications

References 26 publications

Corrosion Initiation and Propagation on Carburized Martensitic Stainless Steel Surfaces Studied via Advanced Scanning Probe Microscopy

Corrosion Initiation and Propagation on Carburized Martensitic Stainless Steel Surfaces Studied via Advanced Scanning Probe Microscopy

Failure stress modification in fatigue life models for rolling bearings

Interaction of anti‐wear additiveTCPwith advanced bearing steels

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