A comprehensive investigation of the strengthening effects of dislocations, texture and low and high angle grain boundaries in ultrafine grained AA6063 aluminum alloy

Journal Article · Thu Feb 15 04:00:00 EST 2018 · Materials Characterization

DOI:https://doi.org/10.1016/J.MATCHAR.2017.12.004· OSTI ID:22804882

Najafi, S.; Samaee, M.; Jafarian, H. R. ^[1]; Zhou, J. ^[2]

---

1. School of Metallurgy and Materials Engineering, Iran University of Science and Technology, Tehran (Iran, Islamic Republic of)
2. Department of Biomechanical Engineering, Delft University of Technology, Mekelweg 2, 2628 CD Delft (Netherlands)

Highlights: • Evolution of microstructure and mechanical properties of AA6063 after severe plastic deformation was investigated. • Average cell size shows a more solid relationship with mechanical properties rather than the average grain size. • This indicates that in addition to high angle boundaries, cell boundaries play a strengthening role. - Abstract: The effect of equal channel angular pressing (ECAP) on the microstructure and mechanical properties of AA6063 aluminum alloy was investigated. For this purpose, samples of AA6063 aluminum alloy were deformed up to 10 passes using ECAP and the evolution of microstructure, texture and dislocation density was investigated. It was found that the dislocation density increased and cells mostly surrounded by low angle boundaries (LABs) formed after 2 passes ECAP. Increasing the dislocation density continued with further processing and reached a maximum at the 4th ECAP pass. With further deformation to 6 passes, the dislocation density reduced, the fraction of high angle boundaries (HABs) increased and the averages of cell size and grain size reduced, significantly, which indicated the occurrence of grain refinement. However, a slight increase in dislocation density, average cell size (ACS) and average grain size (AGS), indicating coarsening, occurred when 10 passes of ECAP are imposed. Hardness, yield (YS) and ultimate tensile strength (UTS) increased continuously although the most significant enhancement occurred after 2 passes of ECAP. Investigating the correlation between the microstructure and mechanical properties indicated that Hall-Petch relationship was valid for ultrafine grained AA6063 before the coarsening started provided that the property of interest was correlated to average cell size but not the average grain size.

• OSTI ID: 22804882
• Journal Information: Materials Characterization, Journal Name: Materials Characterization Vol. 136; ISSN 1044-5803; ISSN MACHEX
• Country of Publication: United States
• Language: English

Related Subjects

36 MATERIALS SCIENCE
ALUMINIUM ALLOYS
DEFORMATION
DISLOCATIONS
GRAIN BOUNDARIES
GRAIN REFINEMENT
GRAIN SIZE
HARDNESS
PLASTICITY
SOLIDS
TENSILE PROPERTIES