Work hardening response of M50-NiL case hardened bearing steel during shakedown in rolling contact fatigue

Abstract

The work hardening response during shakedown phase for case hardened M50-NiL bearing steel in rolling contact fatigue (RCF) is presented. Rolling contact fatigue testing is performed using a ball rod tester for varying cycles and Hertzian stress of 5?5 GPa on multiple test tracks of a case hardened rod. Longitudinal sectioning and polishing of the test rod reveal the RCF affected zones. Micro-Vickers indentation mapping of the subsurface zones is used to measure workhardening. A maximum increase in hardness from 7?4 to 8?3 GPa was observed at y13?5610 6 cycles, after which hardness saturated. A finite element simulation of the RCF test was performed to predict the increase in hardness. It is hypothesised that plastic strain accumulation around the hard carbide inclusions results in increased hardness. Cyclic hardening likely saturates when the ratchet strain per cycle approaches zero. Plastic shakedown follows with no further accumulation of plastic strain and marks the beginning of steady state response.

Critical Assessment 13: Elimination of white etching matter in bearing steels

“…9 The persistent carbides in these secondary hardening steels are used to explain the accumulation of plastic strain in affected regions that are not localised. 59 Butterflies are known to form at high contact stresses even in the M50/M50NiL alloys, 21 but have not been reported in any study from bearings that have experienced service. 60 Indeed, rolling contact fatigue is not a key feature in the failure of aeroengine bearings: the vast majority of operational failures in M50/M50NiL bearings are due to surface distress; [61][62][63] although such distress can initiate cracks that grow by a fatigue mechanism, leading eventually to spalling, the important Bhadeshia and Solano-Alvarez Elimination of white etching matter in bearing steels Materials Science and Technology 2015 VOL 31 NO 9 distinction is that initiation does not begin below the surface where rolling contact stresses are maximal.…”

Numerical analysis of hydrogen-assisted rolling-contact fatigue of wind turbine bearings

“…This way, this paper helps to gain a better understanding of the influence of hydrogen on the life in service of offshore wind turbine bearings through a numerical study. So, the widely used RCF ball-on-rod test [10][11][12][13] was simulated by finite element method to obtain the stress-strain state of bearings during life in service and, from this, to elucidate the potential places where the hydrogen could be more harmful causing final catastrophic failure by hydrogen embrittlement (HE) related phenomena. O NUMERICAL MODELING he study was divided into two uncoupled analysis.…”

Contact Deformation Analysis of Elastic–Plastic Asperity on Rough Roll Surface in a Strip Steel Mill

“…Contact fatigue, rolling contact fatigue (RCF) for instance, is a popular topic in the field of material fatigue. Many researchers have paid attention to RCF under various application backgrounds, such as rolling bearings [12], gears [13], rail steels [14], etc. In strip rolling process, roll fatigue is exhibited by surface cracks and spallings (Fig.…”