Structure and properties of aluminum alloy system Al-Mg-Si after processing by the method of Multi-ECAP-Conform

E.I. Fakhretdinova1, E.V. Bobruk1,2, G.Yu. Sagitova1, G.I. Raab1,3
1Ufa State Aviation Technical University, 12 K. Marx St., Ufa, 450000, Russia
2Saint Petersburg State University, 28 Universitetsky pr., Peterhof, Saint Petersburg, 198504, Russia
3Kazan Federal University, 35, Kremlevskay, Kazan, 420008, Russia
Abstract
The microstructure of a billet from the Al-Mg-Si system after processing by the method of Multi-ECAP-Conform was investigated and its mechanical and electrical properties were defined. The main feature of this method is the combination of two techniques of equal channel angular pressing (ECAP): pressing with parallel channels (ECAP-PC) and continuous pressing according to the Conform scheme (ECAP-Conform). The level of true strain e>2.5 is achieved for one cycle of processing of the billet by the method of Multi-ECAP-Conform. It was revealed that one processing cycle of an aluminum alloy billet of the Al-Mg-Si system by the Multi-pressing-Conform technique allows to form a mixed structure with the subgrains, dominantly elongated along the direction of shear deformation. Formation of separate zones, having equiaxed grains with an average size of 460 nm is observed in the structure. It was shown that the refinement of the aluminum matrix is accompanied with the formation of nanosized particles of secondary hardening phase of Mg2Si. Evaluation of properties of the aluminum alloy after processing of a billet by the method of Multi-ECAP-Conform was made. It was revealed that as a results of formation of the UFG structure (cold work and disperse hardening) the conventional yield stress (YS) and tensile strength (UTS) increased from 120 and 180 MPa to 221 and 243 MPa and the electrical conductivity (IACS) increased from 51.3 to 54.3 % in comparison with the as-received condition (T1).
Accepted: 28 May 2015
Views: 147   Downloads: 43
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