A novel approach for modeling retained austenite transformations during rolling contact fatigue

Abstract

Retained austenite (RA) transformation in martensitic steels subjected to rolling contact fatigue (RCF) is a well‐established phenomenon. In this investigation, a novel approach is developed to predict martensitic transformations of RA in steels subjected to RCF. In order to achieve the objectives, a 2‐dimensional finite element model was developed to determine subsurface stresses due to rolling contact. These stresses are utilized within a continuum damage mechanics framework to determine RA transformations as a function of depth and cycles. Phase transformations were determined by comparing the required thermodynamic driving force for transformations to the energy dissipation of the microstructure. The results obtained from the combined FEA and continuum damage mechanics model were corroborated to the experimental results for RA decomposition as a function of depth and cycle for SAE 52100 steel. The results obtained are in good agreement with observed RA decomposition and DER formation as compared with the experimental results.

Further understanding of rolling contact fatigue in rolling element bearings - A review

“…It is believed that the microstructural alterations in bearing steels occur at the steady-state response stage or even as early as the plastic shakedown stage of RCF where a steady state plastic flow is present [97,143,144]. DERs usually form under moderate to high contact stress in the area of maximum shear stress after a large number of rolling cycles (5-100 million cycles) [2,13,87,88,90,97,[145][146][147]. In accordance with the contact geometry and loaddependent depth of maximum shear stresses, the depth of the region has been found to vary from approximately 0.1-0.65 mm beneath the contact surface.…”

Retained austenite stability on rolling contact fatigue performance of 8620 case‐carburized steel

“…Thus, our previously developed 2D continuum damage mechanics (CDM) finite element model (FEM) was further modified to investigate the effects of RA stability (E T ) on RCF performance. The RCF CDM ABAQUS FE model described in previous works 26,27 will be briefly described here. Figure 8A depicts the ABAQUS domain developed and used in this investigation.…”

“…This reduces the barrier restricting the phase transformation from occurring until the transformation may occur spontaneously. Morris et al 26 combined damage mechanics with principles of phase transformations in solids to formulate an energy criteria to predict RA transformations during a fatigue process. This was accomplished by recognizing that the Gibb's free energy enthalpy term could be directly related to the damage.…”

“…In Equation (8), are the change in the specific Gibbs free energy to drive the phase transformation, the elastic contribution, the plastic contribution attributed to kinematic hardening, the material density, the change in stress, and corresponding plastic strain, respectively 26 . The elastic contribution , Equation (9), is calculated from the equivalent von Mises stress σ eq , the elastic modulus E , the damage variable D , and the triaxiality function defined in Equation (10), where ν and σ H are the Poisson's ratio and hydrostatic stress, respectively.…”