STRUCTURE REFINEMENT BY SPD AND PROPERTIES RESPOND OF AA6082 ALUMINUM ALLOY

1 ZRNIK Jozef
Co-authors:
2 SCHERIAU Stephan 2 PIPPAN Reinhard 1 SLAMA Peter
Institutions:
1 COMTES FHT Inc., Dobrany, Czech, Republic
2 Erich-Schmid Institute of Materials Science, Austrian Academy of Science, Leoben, Austria
Conference:
24th International Conference on Metallurgy and Materials, Hotel Voronez I, Brno, Czech Republic, EU, June 3rd - 5th 2015
Proceedings:
Proceedings 24th International Conference on Metallurgy and Materials
Pages:
1233-1239
ISBN:
978-80-87294-58-1
ISSN:
2694-9296
Published:
12th January 2015
Proceedings of the conference were published in Web of Science and Scopus.
Metrics:
299 views / 124 downloads
Abstract

In this study ultrafine grain structure evolution during high pressure torsion of commercial aluminum alloy AA6082 at increased temperature is presented. Two different initial states of the alloy were prepared by thermal treatment. The progress in structure refinement in dependence on the shear strain level was investigated by TEM in thin foils. The impact of different amount of strain εef was analyzed with respect to the effect of increased temperature. The results of microstructure analyses confirmed that ultrafine grain (UFG) structure was already formed in deformed disc upon the first turn, regardless the initial structure of alloy. The heterogeneity in UFG grain structure development across the deformed discs was observed in thin foils, supporting by micro hardness results scattering. By increasing strain value, applying different number of turns (N-2,4,6), more effectively homogenized UFG microstructure was observed across the deformed discs. The effect of increased deformation temperature became evident and dynamic recrystalization modified locally received UFG structure. The retardation of new grains growth and higher thermal stability of UFG structure was observed, when two steps thermal treatment of alloy, introducing quenching and ageing, was executed prior sample deformation. The strength measurement results, yielded from tensile tests, showed that the effect of structure strengthening was degraded by local recrystallization of deformed structure. The results received at torque measurements versus the time then showed that the torque required to deform the sample was increasing until the first turn and then kept stable or even decreased.

Keywords: Aluminum alloy, ultrafine grain structure (UFG), pressure torsion, torque, deformation behavior

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