Multi-scale modelling of AISI H11 martensitic tool steel surface anisotropic mechanical behaviour

Ahmed Zouaghi,Farhad Rézaï-Aria,Adriana Soveja,Vincent Velay

doi:10.1051/matecconf/20141204018

Ahmed Zouaghi, Farhad Rézaï-Aria + Show 2 more

Open Access

https://doi.org/10.1051/matecconf/20141204018

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Abstract

In this work, a numerical investigation is carried out on the anisotropic and heterogeneous behaviour of the AISI H11 martensitic tool steel surface using finite element method and a multi-scale approach. An elasto-viscoplastic model that considers nonlinear isotropic and kinematic hardenings is implemented in the finite elements code ABAQUS using small strain assumption. The parameters of the constitutive equations are identified using macroscopic quasi-static and cyclic material responses by the mean of a localization rule. Virtual realistic microstructures, consisting of laths and grains, are generated using particular Voronoi tessellations. These microstructures consider the specific crystallographic orientations α’/γ. Finite element investigation is then performed. The local heterogeneous and anisotropic behaviour of the surface as well as the subsurface is shown under quasi-static and cyclic mechanical loadings. The laths morphology and crystallographic orientation have an important impact on the local mechanical fields.

Highlights

During forming and machining processes, surface and subsurface of metallic materials are experiencing cyclic thermo-mechanical and quasi-static loadings in particular shearing
The microstructure on subsurface presents a pronounced anisotropic microstructural aspect resulting from shear strain gradient and the grain crystallographic orientations, morphology, and grains interactions, that develops a textured grains and gradient beneath the surface
A multi-scale modelling is used to describe the local behaviour of an AISI H11 martensitic hot work tool steel surface

Summary

Introduction

During forming and machining processes, surface and subsurface of metallic materials (both tools and parts) are experiencing cyclic thermo-mechanical and quasi-static loadings in particular shearing. Under such solicitations, the microstructure on subsurface presents a pronounced anisotropic microstructural aspect resulting from shear strain gradient and the grain crystallographic orientations, morphology, and grains interactions, that develops a textured grains and gradient beneath the surface. Many investigations on thermo-mechanical behaviour and life assessments of metallic materials use macroscopic models [1, 2] They consider in general the microstructure as an isotropic and homogeneous media by neglecting any microstructural heterogeneity. To better get insight into the local mechanical behaviour of the surface, a multi-scale approach is very much of concern for life prediction of metallic alloys by taking into account the microstructure anisotropic aspects

Numerical methodology

Principle results