Investigation of mesoscale deformation and damage behaviour in high-carbon bearing steel via multiscale simulations and experiments

Abstract. High-carbon steel is susceptible to micro-defects owing to the heterogeneous microstructures during forming, which seriously deteriorates the fatigue life. However, the investigation of the damage behavior during cold deformation remains largely undisclosed in these steels, which hinders further control of the microstructure and forming process. The current work investigates the deformation and damage characteristics of high-carbon steel composed of soft ferrite and hard cementite particles. A methodology coupled with multiscale simulations and experiments is applied to analyze large plastic deformation and damage characteristics. The simulation utilizes nanoscale molecular dynamics simulation to obtain matrix-particle interface strength properties. The Rice-Tracey fracture model and Weibull distribution capture experimental fracture characteristics of matrix and particles. The above failure criteria are incorporated within a real microstructure-based representative volume element (RVE) to conduct the mesoscale deformation and damage process in the spheroidized ferrite-cementite steel. Additionally, in-situ SEM uniaxial tensile tests are carried out to assess the damage mechanism and validity of the mesoscale simulation. The numerical simulation exhibits a well coincidence with the experimental trends in damage evolution of the individual particles, matrix, and matrix/particle interfaces. It is also observed that damage is a function of inherent particle properties, particle morphological features, and matrix strain localization characteristics. Larger-size and long-striped particle undergoes fracture at an earlier stage. Consequently, the incompatibility and stress concentration between matrix and particles affect the strain localization characteristics. As a result, higher stresses inside strain localization bands results in the increase of void damage initiation and growth along the interfaces. Overall, the way of matrix/particle decohesion should be marginally higher compared to particle fracture, which primarily dominates the final fracture of the high-carbon bearing steel.