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Effect of A1 ₃(Sc,Zr) dispersoids on the hot deformation behaviour of 6xxx-series alloys: a physically based constitutive model

journal contribution
posted on 2020-08-01, 00:00 authored by Steven Babaniaris, Mahendra RamajayamMahendra Ramajayam, Lu JiangLu Jiang, Ramesh Kumar VarmaRamesh Kumar Varma, T Langan, Thomas DorinThomas Dorin
The hot deformation behaviour of two model Al–Mg–Si alloys was assessed. One alloy was representative of the 6xxx series containing small additions of Mn and Cr, while the other contained small additions of Sc and Zr. Prior to deformation, a multi-stage heat treatment was conducted on the alloys to solutionize the Mg and Si and promote the precipitation of Al3(Sc,Zr) dispersoids in the Al–Mg–Si-Sc-Zr alloy. Uniaxial hot compression tests were conducted at various temperatures (683–823 K) and strain rates (1–125 s−1) and the resulting flow stress-strain curves were evaluated. Flow stress values were observed to be slightly increased in the alloy containing Sc and Zr. The activation energy for hot deformation and material constants for each alloy were calculated, which in turn provided a good prediction of the experimental data. The post-deformation microstructures were analysed using SEM and TEM. The capacity for dynamic recovery was reduced, while dynamic recrystallization was prevented in the Al–Mg–Si-Sc-Zr alloy. This was a result of restricted dislocation motion, caused by the pinning of dislocations from the Al3(Sc,Zr) dispersoids. The relative flow stress of the Al–Mg–Si-Sc-Zr alloy was found to compare favourably to other 6xxx series alloys with similar mechanical properties.

History

Journal

Materials science and engineering A

Volume

793

Article number

139873

Pagination

1 - 13

Publisher

Elsevier

Location

Amsterdam, The Netherlands

ISSN

0921-5093

Language

eng

Publication classification

C1 Refereed article in a scholarly journal