Local fracture strain measurement in AHSS uniaxial flat tensile tests considering specimen geometry and fracture morphology

P. Larour, L. Wagner, A. Felbinger, J. Angeli

Research output: Contribution to journalConference articlepeer-review

1 Citation (Scopus)

Abstract

The local formability of AHSS sheet steels can be estimated by means of the relative average reduction of cross section area (or thickness) at fracture in flat tensile specimens. A 2D/3D characterization of tensile fracture shapes is performed with an optical stereo microscope for various typical fracture shapes. The initial width to thickness ratio (w0/t0) of flat tensile samples quantifies their non-proportionality behavior. A charpy like lower and upper shelf region with a highly scattered transition zone in between at a critical w0/t0 ratio is observed when plotting the fracture area or thickness reduction versus w0/t0 ratio. The higher the w0/t0 ratio of tensile specimens (samples wider, material thinner) the higher the local fracture strain level. The higher the material work hardening ability (n-value), the higher the critical w0/t0 ratio below which high scattering in thickness - and area reduction occurs. The local tensile fracture strain is therefore strongly dependent on specimen thickness, width and work hardening behavior. This is a severe drawback for a broader use of such tensile test based fracture strain measurements.

Original languageEnglish
Article number012016
JournalIOP Conference Series: Materials Science and Engineering
Volume651
Issue number1
DOIs
Publication statusPublished - 26 Nov 2019
Event38th International Deep Drawing Research Group Annual Conference, IDDRG 2019 - Enschede, Netherlands
Duration: 3 Jun 20197 Jun 2019

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