Microstructure and Mechanical Properties of 6013 Aluminium Alloy Processed by a Combination of ECAP and Preaging Treatment (original) (raw)
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Evolution of the Microstructure of Al 6082 Alloy during Equal-Channel Angular Pressing
Materials Science Forum, 2005
A commercial Al-Mg-Si alloy (Al 6082) was deformed by Equal-Channel Angular Pressing (ECAP) to produce bulk ultrafine-grained microstructure. The crystallite size distribution and the characteristic parameters of the dislocation structure were investigated by X-ray diffraction profile analysis. It was found that the crystallite size decreased and the dislocation density increased during ECAP deformation. The increase of the yield stress of the alloy was related to the increase of the dislocation density using the Taylor model. Materials Science Forum Vols. 473-474 (2005) pp. 453-458 online at http://www.scientific.net
Solid State Phenomena
The purpose of this paper is to present the microstructure and mechanical behavior of 6060 aluminum alloy after intense plastic deformation. Equal Channel Angular Pressing (ECAP) was used as a method of severe plastic deformation. Before ECAP part of the samples were heat treated to remove internal stresses in the commercially available aluminium alloy. The evolution of microstructure and tensile strength were tested after 1, 3, 6 and 9 ECAP passes in annealed and non annealed states. It was found that intensely plastically deformed refined grains were present in the tested samples and exhibited increased mechanical properties. Differences were noted between samples without and after heat treatment
The mechanical properties and microstructure of EN AW 6082 aluminium alloy subjected to severe plastic deformation (SPD) and natural ageing are compared with those of extruded and artificially aged state (initial state) and quenched state of alloy after solution annealing. Quenched state of alloy was deformed at room temperature by equal channel angular pressing (ECAP) following route C up to three passes. Polyedric microstructure of quenched state was considerably changed by SPD. Deformation bands with different amount of deformation were observed in microstructure of ECAPed state, which indicated non-uniform deformation across the cross-section of ECAPed specimen. Ultimate tensile strength (UTS) and especially yield strength (0.2% YS) were considerably increased by SPD, but plasticity was decreased. Increase of strength of ECAPed state was first of all evoked by the deformation strengthening.
Materials & Design, 2015
Sever plastic deformation processing has been frequently used to refine grain size and to improve properties in metals and alloys. The impact of combination of equal channel angular pressing (ECAP) and precipitation hardening on mechanical properties of 6063 aluminum alloy was investigated in this paper. These two processes were also tested individually in order to know if the combination affects the microstructure and tensile properties. According the experimental results, the yield and ultimate strength increase twice and three times respectively after ECAP processing. Having the processed samples naturally aged, the microstructure and mechanical properties remain almost unchanged. However, artificial aging at 180°C after ECAP, improves the ductility of the material and decreases the strength slightly due to dislocation annihilation occurring during heat treatment. It can be deduced that individual processes of ECAP and aging enhance some mechanical properties and worsen some others; but combination of these processes improves the material's properties. In order to compare quantitatively the overall mechanical properties a new factor, denoted by SNMP, is introduced which is the Sum of Normalized Mechanical Properties. According to the results, the value of SNMP for combination of processes is much higher than that for individual processes.
Microstructure behavior of Al–Mg–Sc alloy processed by ECAP at elevated temperature
Acta Materialia, 2008
Microstructural evolution taking place during equal channel angular pressing (ECAP) was studied in a coarse-grained Al-6% Mg-0.4% Mn-0.3% Sc alloy at 300°C ($0.6T m ). Samples were pressed to strain 12 and quenched in water after each pass. ECAP at moderate-to-high strains leads to formation of a bimodal grain structure, with grain sizes of about 1 and 8 lm and volume fractions of 0.3 and 0.6, respectively. The development of new-grained regions has been shown to result from the concurrent operation of the continuous dynamic recrystallization that occurs during deformation and the static recrystallization that occurs by the exposure of the as-deformed material in the die kept at 300°C and/or reheating between pressings. The microstructural development is discussed in terms of the enhanced driving force for recrystallization, resulting from the evolution of high-density dislocation substructures due to localization of plastic flow and inhibition of recovery in the present alloy.
Materials Science and Engineering: A, 2008
Deformation structures of a commercial Al-Mg-Si alloy (6082) processed by equal-channel angular pressing at room temperature were characterized by transmission electron microscopy. Deformation twins, which have never been observed in coarse-grained aluminium, were experimentally confirmed together with numerous other features. The possible roles of twinning and different grain boundary structures on the severe plastic deformation (SPD) mechanisms, including grain refinement, were discussed.
Microstructure Evolution of AA7050 Al Alloy During Equal-Channel Angular Pressing
Materials Research-Ibero-American Journal of Materials, 2012
High strength AA7050 aluminum alloy was processed by ECAP through route A in the T7451 condition. Samples were processed at 423 K, with 1 and 3 passes. The resulting microstructure was evaluated by optical microscopy (OM), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). The phases were identified by X-ray diffraction (XRD) using monochromatic Cu Kα radiation. Rockwell B hardness and tensile tests were performed for assessment of mechanical properties. The microstructure was refined by the formation of deformation bands, with dislocation cells and elongated subgrains, with an average width of 240 nm, inside these bands. The number of deformation bands increased with the number of passes. A reduction of precipitates size was observed with increase in the number of passes, when compared to initial condition, probably resulting from particle fragmentation during ECAP. After three passes the precipitates tend to a more equiaxed morphology and have sizes smaller than 10 nm. Phases η' and η coexist in the microstructure, but η is the dominant phase, mainly after three passes. The hardness of alloy after the first pass of ECAP is almost equal to the initial condition. After three passes the hardness showed a slight reduction which must be result from recovery process. There was a slight improvement in the yield strength and elongation after one pass, when compared to the initial T7451 condition. The improvement in the ultimate tensile strength was less significant.
Transactions of Nonferrous Metals Society of China, 2014
Structural features, aging behavior, precipitation kinetics and mechanical properties of a 6013 Al-Mg-Si aluminum alloy subjected to equal channel angular pressing (ECAP) at different temperatures were comparatively investigated with that in conventional static aging by quantitative X-ray diffraction (XRD) measurements, differential scanning calorimetry (DSC) and tensile tests. Average grain sizes measured by XRD are in the range of 66−112 nm while the average dislocation density is in the range of 1.20×10 14 −1.70×10 14 m −2 in the deformed alloy. The DSC analysis reveals that the precipitation kinetics in the deformed alloy is much faster as compared with the peak-aged sample due to the smaller grains and higher dislocation density developed after ECAP. Both the yield strength (YS) and ultimate tensile strength (UTS) are dramatically increased in all the ECAP samples as compared with the undeformed counterparts. The maximum strength appears in the samples ECAP treated at room temperature and the maximum YS is about 1.6 times that of the statically peak-aged sample. The very high strength in the ECAP alloy is suggested to be related to the grain size strengthening and dislocation strengthening, as well as the precipitation strengthening contributing from the dynamic precipitation during ECAP.
Acta Materialia, 2010
The present paper analyzes the effect of the equal channel angular pressing (ECAP) routes A and Bc on the recrystallization conditions and mechanical properties of Al-5086 alloy. The specimens were processed up to 10 passes at 150 º C in a die with 120 º inner angle. The recrystallized grains developed after the tenth pass in the route A. By increasing the number of passes the grains became finer and after the tenth pass, the average grain size became finer than 2 m. The tensile and hardness tests results showed that in all passes, the route Bc had a stronger effect on the simultaneous improvement of strength and ductility. The fracture surfaces analyses showed that the local ductile behavior improves as increasing the number of passes. The textures analyses showed that the dominant component was altered from (111) to (200) and (220) plane by increasing the number of passes through both routes. Also, the dislocation density increased by increasing the number of passes.
Archives of materials science and engineering, 2016
Purpose: The main goal of this paper is to present the investigation results of microstructural evolution and mechanical properties changes in commercial EN AW 6060) aluminium alloy after intensive plastic deformation, obtained by equal channel angular pressing (ECAP) techniques in an annealed state. Design/methodology/approach: Annealing heat treatment was used to remove various types of internal stress in a commercially available alloy in order to increase workability of the material. The evolution of its properties and material behaviour was evaluated after 2,4,6,and 8 passes of the ECAP process. Findings: It was found that the mechanical properties and microstructure during intensive plastic deformation, such as that during the ECAP process, were changed. Plastic deformation refined grains in the aluminium alloy and increased its mechanical properties. Research limitations/implications: The presented study shows results of the investigated material in an annealed state. Practica...