P52 - Dispersion Hardening Effect of Dispersoids in 3xxx Al Alloys With Varying Manganese and Silicon Contents: Eva Mørtsell1; Astrid Marie Muggerud1; Yanjun Li2; Randi Holmestad1; 1NTNU; 2Sintef The goal of this project is to quantify the amount, distribution and composition of particles/dispersoids in four selected AA3XXX aluminium alloys with high and low Si content at different heat treatments. For non-heat treatable alloys the strengthening occurs from solid solution formation, second phase microstructural constituents, dispersoids and/ or strain hardening. The microstructure is correlated with mechanical properties such as hardness, electrical conductivity and tensile properties. The samples studied are isothermally annealed at temperatures between 350 and 450°C and then quenched to room temperature after holding times of 0h, 1h, 4h, 8h, 24h and 48h. The heating rate was 50°C per hour, starting from room temperature.The main investigation tool is advanced analytical Transmission Electron Microscopy together with Electron Energy Loss Spectroscopy for determining the thickness of the samples in question. Quantitative measures of size, density and volume fraction of dispersoids are related to the measured mechanical properties. P53 - Effect of Hot Extrusion Conditions on the Microstructure of AA3003: Lina Grajales1; Warren Poole1; Yahya Mahmoodkhani2; Mary Wells2; Nick Parson3; 1University of British Columbia; 2Univeristy of Waterloo; 3Arvida Research and Development Centre There is significant interest in the microstructural development during extrusion of AA3xxx aluminum alloys, which are used in heat exchanger applications. The ability to control deformation conditions allows for the design of the microstructure so that the material properties can be tailored to the final component. A systematic study of processing conditions for AA3003 was conducted using a laboratory scale fully instrumented extrusion press. Billets previously homogenized at different conditions were extruded with a variety of extrusion ratios and ram speeds. Extrusion samples were characterized with the use of optical microscopy. A full range of microstructures from recrystallized to unrecrystallized, with a wide range of final grain sizes and spatial variation were obtained. The results have been rationalized in comparison with processing conditions from the trials. P54 - Effect of Iron and Silicon on Strength and Electrical Resistivity of Al-Zr Wire Alloys: Alexander Alabin1; Nikolay Belov1; 1MISIS We have studied the effect of iron (up to 0.3 wt.%) and silicon (up to 0.2 wt.%) on the structure, electrical resistivity and strength of Al-Zr wire alloys (up to 0.70 wt.% Zr) after various annealing regimes. The phase composition of the Al–Zr–Fe–Si system was analyzed with respect to newgeneration heat resistant wire aluminum alloys. By the use of Thermo-Calc software we calculated the solubilities of Zr, Fe and Si in aluminum solid solution-(Al) and volume fractions of all possible phases (including Al3Zr -L12 nanoparticles) at various temperatures. In contrast with unalloyed aluminium (AA1350) silicon addition to Al-Zr alloys allows to obtain an optimal combination of electrical and mechanical properties. By the use of desirability function it is shown that all experimental Al-Zr alloys have the best combination of strength, electrical resistance and thermal stability after technological process with intermediate annealing.
P56 - Influence of the Chemical Composition on the Structure and Properties of Lead-Free Machinable AA6023 (Al-Mg-Si-Sn-Bi) Alloy: Jiri Faltus1; Miroslav Karlik2; Petr Haušild2; 1Research Institute for Metals; 2Czech Technical University in Prague Microstructure and properties of extruded rods of a new machinable lead-free aluminum AA6023 (Al-Mg-Si-Sn-Bi) alloy having different levels of Mg content were characterized. In the structure of the alloy there are low-melting point particles containing Sn+Bi. During machining, the temperature generated in the cutting zone is high enough to melt these dispersed entities. This melting gives rise to a local loss of the material strength and ductility which in turn leads to the formation of short, discontinuous chips. In addition to tin and bismuth, some of the Sn+Bi particles contain also a high amount of magnesium and intermetallic compounds of Mg2Sn and Mg3Bi2 are thus formed. The presence of these stable phases increases the melting temperature of Sn+Bi containing particles and their originally positive impact on improving the machinability is therefore reduced. Hence increasing of Mg content in the Al-Mg-Si-Sn-Bi alloy reduces its machinability. P57 - Effect of Thermomechanical Treatment on Sag Resistance of Roll-Bonded High Strength Aluminum Clad Sheets: Kwangjun Euh1; Hyoung-Wook Kim1; Suk Bong Kang1; 1Korea Institute of Materials Science Lightweight aluminum clad sheets are widely used for brazing materials in the automotive heat exchangers. In order to achieve further light-weight of the components, thinner brazing sheets with high strength is required, where the strength of the clad sheet is proportional to that of the core alloy. In the present study, strip-cast aluminum alloys having high strengths are used as core alloys for aluminum clad sheets. The high strength clad sheets are fabricated by the roll bonding process and further cold-rolled down to the thickness of 0.08 mm. Cold rolling is interrupted by full annealing at the different amount of reductions in order to obtain the thin aluminum clad sheets with different final reductions. The effect of thermomechanical treatment on the sag resistance of high strength aluminum clad sheet is elucidated by means of microstructural analysis. P58 - Homogenisation of 6xxx Alloy Ingots with an Addition of Vanadium: Marzena Lech-Grega1; Wojciech Szymanski1; Mariusz Bigaj1; Maciej Gawlik1; 1Institute of Non-Ferrous Metals The selection of material for elements operating in the crumple zone should consider the mechanical properties of alloys and their ability to absorb energy. Undoubtedly, such materials include aluminium alloys with an addition of vanadium. The aim of this study was to evaluate the impact of homogenisation conditions on the structure and properties of ingots cast by DC technique at different solidification rates from alloys included in the 6xxx series, such as AlMgSi and AlMgSiCu with an addition of 0.2 wt% and 0.4 wt% vanadium. The alloy structure was examined by light microscopy and scanning electron microscopy combined with an EDX analysis. Changes in mechanical properties were determined by hardness measurements and static compression test after different time/temperature variants of the homogenising treatment. Optimum parameters of the homogenising process were determined for the examined ingots and an extension of the homogenisation time was considered justified only for ingots containing Cu.
13th International Conference on Aluminum Alloys
Posters
P55 - Effect of Prior State on the Microstructural Evolution in a Al-Cu-Mg-Ag Alloy during ECAP at 250°C: Marat Gazizov1; Rustam Kaibyshev1; 1Belgorod State University The effect of prior state on evolution of deformation microstructure and phase composition during equal channel angular pressing (ECAP) of an Al-Cu-Mg-Ag alloy with small additions of zirconium and scandium was studied in present paper using scanning electron microscopy (SEM), transmission electron microscopy (TEM) and X-ray analysis. ECAP was conducted at 250°C by using route BC to strains ranging from 1 to 12. It was found that optimal prior state for subsequent deformation is overaging at 380°C for 3 h. In this condition after 12 passages of pressing the formation
of recrystallized structure with fraction of high angle boundaries (HAB) of ~0.7, average misorientation angles of ~33° and grain size of ~1 µm are observed. In case of overaging the precipitation of particles of the stable S-phase (Al2CuMg) and Ag-enriched phases were observed after pressing to strain ranging from 1 to 12. The effect of different types of the particles on dynamic recrystallization (DRX) mechanisms and opportunity of static recrystallization (SRX) evolution due to particle stimulated nucleation (PSN) are discussed in detail.
103