A new methodology based on X-ray micro-tomography to estimate stress concentrations around inclusions in high strength steels

This work aims at improving the calculation of stress fields around non-metallic inclusions in high strength bearing steels. A new methodology is proposed, based on: (i) the determination of 3D morphologies of inclusions by X-ray micro-tomography imaging; (ii) the characterization of the mechanical properties of the inclusion by nano-indentation, and (iii) finite element (FE) calculations of the stress concentration induced by the inclusions. The methodology is applied to a calcium aluminate inclusion with cavities, located in a Hertzian stress field. The stress concentration appears to be strongly dependent on the orientation of the inclusion-cavity considered. The stress concentration fields obtained from realistic 3D shapes are compared to those obtained from simplified shapes of inclusions.