Differential hardening in IF steel - Experimental results and a crystal plasticity based model

Hans Mulder, Philip Eyckens, Ton van den Boogaard*

*Corresponding author for this work

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Work hardening in metals is commonly described by isotropic hardening, especially for monotonically increasing proportional loading. The relation between different stress states in this case is determined by equivalent stress and strain definitions, based on equal plastic dissipation. However, experiments for IF steel under uniaxial and equibiaxial conditions show that this is not an accurate description. In this work, the determination of the equibiaxial stress–strain relation with 3 different tests will be elaborated: a stack compression test, a cruciform tensile test and a bulge test. A consistent shape of the hardening curve is obtained which deviates from that of a uniaxial tensile test. Several physical explanations based on crystal plasticity are considered, including texture evolution, strain inhomogeneity and glide system hardening models. Texture evolution changes the shape of the yield surface and hence causes differential hardening, however, the observed differences at low strains cannot be explained by texture evolution. Accounting for the strain heterogeneity in the polycrystal, with equilibrium of forces over grain boundaries, improves the prediction of differential hardening considerably, even with a simplified interaction model (Alamel) and simple hardening laws for the glide systems. The presentation is based on a recently published paper by the authors [1].
Original languageEnglish
Title of host publicationAdvanced constitutive models in sheet metal forming
Subtitle of host publication8th Forming Technology Forum Zurich 2015: Proceedings
EditorsPavel Hora
Place of PublicationZurich
PublisherInstitute of Virtual Manufacturing, ETH Zurich
ISBN (Print)978-3-906031-98-9
Publication statusPublished - 29 Jun 2015
Event8th Forming Technology Forum 2015: Advanced constitutive models in sheet metal forming - ETH Zurich, Zurich, Switzerland
Duration: 29 Jun 201530 Jun 2015


Conference8th Forming Technology Forum 2015


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