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The effect of elastic strain and small plastic deformation on tensile strength of a lean Al-Mg-Si alloy

The effect of elastic strain and small plastic deformation on tensile strength of a lean Al-Mg-Si alloy

Category
Academic article
Abstract
Al–Mg–Si alloys are usually formed into their final shape by rolling or extrusion. After extrusion, the aluminium profiles are usually straightened, causing the material to be subjected to a small plastic deformation. This study demonstrates the positive effect on strength that can be obtained from such small deformation levels or from only elastically straining the material. Elastic straining of a lean Al–Mg–Si alloy, when performed immediately after solution heat treatment, enhances the material yield strength after artificial ageing to T6. Transmission electron microscopy shows that this effect can be attributed to a higher number density and finer dispersion of the age-hardening precipitate needles. Furthermore, introducing a small plastic deformation of 1% after solution heat treatment results in a comparable strength increase to elastically straining the material. In this case, however, the strength increase is due to the increased dislocation density, which compensates for a lower density of precipitate needles. Finally, by combining plastic deformation with a succeeding elastic strain, we demonstrate how elastic strain can cause an on-set of dislocation cell formation in this material.
Client
  • Research Council of Norway (RCN) / 219371
  • Research Council of Norway (RCN) / 197405
Language
English
Author(s)
  • Eva Anne Mørtsell
  • Ida Westermann
  • Calin Daniel Marioara
  • Ketill Olav Pedersen
  • Sigmund Jarle Andersen
  • Jostein Røyset
  • Bjørn Holmedal
  • Randi Holmestad
Affiliation
  • Norwegian University of Science and Technology
  • SINTEF Industry / Materials and Nanotechnology
  • Norsk Hydro ASA
Year
2019
Published in
Metals
ISSN
2075-4701
Publisher
MDPI
Volume
9
Issue
12