Accumulated extrusion is a novel plane strain compression technique, akin to the process of accumulated roll bonding, designed to produce ultrafine grained lamellar materials. AA1050 CP-Al processed by AccumEx displayed a grain refinement from 17 μm to 1.8 μm after 2 passes (equivalent strain of 3.2) with an increase in tensile strength of ≈70%. A comparative study with the conventional equal channel angular extrusion technique demonstrated that the former displayed a higher fraction of high angle grain boundaries with very similar trend of grain refinement. Up to now, extrusions up to 8 passes have been performed.
The plastic behavior of face-centered cubic metals was investigated over a wide range of strain and testing temperature. The experimental stress-strain data were described using both macroscopic and microscopic, well-established relationships. The characteristics of these descriptions are discussed and compared with each other. The analysis of the characteristics leads to a definition of the low and high temperature deformation regions, where the kinetics of both the dislocation-multiplication and the dislocation-annihilation (recovery) are different. For pure aluminum, it is shown that the boundary between these two regions occurs at a homologous temperature of the order of ≈ 0.5 T_{m} where T_{m} is the absolute melting temperature. From this analysis, correlations are also drawn between the macroscopic parameters describing the stress-strain relationship and the fundamental characteristics of the microscopic processes both at room temperature and elevated temperatures.
The present transmission lines of populous cities will have to be changed with an ability to work at higher temperatures without any weight and cross section changes. Innovative thermal-resistant alloy conductors (T-ACSR) operate in the range of about 150-200°C instead of 75°C which is the standard ACSR type conductor service temperature. In this study, the manufacturing procedure of Al-Zr alloy wire, used as high-temperature conductor wires, have been introduced. The Al-Zr alloy has been cast in a permanent mold than being extruded to a diameter of 10 mm at 400°C. After that the extruded rods have been cold drawn to a diameter of 3.02 mm. Elongation and tensile strength values of the cold drawn wire have been achieved by tensile test at elevated temperatures. Also, microstructural analysis and dispersion hardening procedure have been investigated. The results show that tensile strength and thermal-resistant property are improved by the addition of Zr.
Magnesium-manganese (Mg-Mn) based alloys with various chemical composition were processed by indirect extrusion at two different speeds. Alloying with Mn and rare earth elements has significant influence on the microstructure and on the texture of the alloys under investigation. This paper deals with the acoustic emission analysis of the deformation behavior of the extruded Mg-Mn alloys. The acoustic emission measurements were performed during the uniaxial tension and compression tests, and the obtained results are discussed with respect to the influence of rare-earth elements on the deformation behavior, particularly in terms of the activation of dislocation glide and twinning.
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