A multi-scale approach to investigate the nonlinear subsurface behavior and strain localization of X38CrMoV5-1 martensitic tool steel: Experiment and numerical analysis

Abstract

The cyclic mechanical behavior, the wear and fatigue resistances and damage developments of working surface of tool steels are dependent on microstructural features. A multi-scale approach combining experimental testing, numerical treatments and simulations is developed to model the surface behavior of X38CrMoV5-1 martensitic tool steels. The multi-scale modeling is coupled with finite element calculations. The elasto-viscoplastic constitutive equations used are based on crystal plasticity model of Méric-Cailletaud and are implemented on the finite element code ABAQUS under a small strain assumption. Trough an appropriate laboratory testing, the microstructure features comparable to the surface of industrial tools or pin/disc in tribology experiments are reproduced by considering plate specimens. Monotonic tensile testing is coupled with in-situ Digital Image Correlation technique (DIC) to determine the surface strain fields. The measured local nonlinear mechanical strain fields are analyzed. The strain localization is related to stereological artifacts. The numerical treatments allow reproducing, qualitatively, the strain localization patterns at the surface observed during tensile testing. The influence of the various stereological parameters such as the morphology of martensitic laths, the crystallographic orientations, the internal hardening state of the surface profiles and their evolutions on the local strain fields are addressed. By such approach, it is possible to get a better insight of some elementary mechanisms acting on tools and/or pin/disc surfaces regarding both tensile and cyclic behavior.