nanocrystalline aluminum. This work investigates how the test conditions affect the mechanical behavior of this material. A full factorial experiment is designed to investigate effects of strain rate, size, material orientation, and coarse grain volume ratios through uniaxial tensile tests. The results are found to conform well to Joshi’s model for plasticity. Strength and ductility is found to decrease with increasing strain rate and specimen thickness is found to affect the stiffness of the material. Increasing coarse grain ratio is found to increase ductility, though it appears that the effect may become saturated at some point. Furthermore, significant anisotropy effects are observed. 3:00 PM Break
3:50 PM Microstructure, Mechanical and Electrical Properties Evolution during Cold Rolling of Different 1xxxx Series Aluminium after Continuous Casting: Tadeusz Knych1; Artur Kawecki1; Grzegorz Kiesiewicz1; Pawel Kwasniewski1; Andrzej Mamala1; Beata Smyrak1; Wojciech Sciezor1; 1AGH - University of Science and Technology Conventional aluminium processing involves continuous casting, hot and cold metal forming and optional heat treatment. Modern processes aim to shorten the cycle of manufacturing and consist cold metal forming after continuous casting. A well-known example of such solutions is the twin-roll casting and cold rolling of aluminium sheets. For these reasons an analysis of the impact of cold deformation on structure and properties of materials after continuous casting and analysis of its quality becomes an important research problem. The paper shows the results of laboratory aluminium continuous casting. The effects of inoculant micro-additions which modify the structure of casts and its effect on the macroscopic properties of the material were examined. The paper also shows the results of laboratory tests of material cold rolling after continuous casting. The mechanical properties of material as a function of cold deformation evolution and a number of utility properties of finished sheets were examined.
TMP 7
Program Organizers: William Cassada, Alcoa Technical Center; Hasso Weiland, Alcoa Technical Center; Anthony Rollett, Carnegie Mellon University Symposium Organizers: Wojciech Misiolek, Lehigh University; Vivek Sample, Alcoa Inc. Wednesday PM June 6, 2012
Room: Wright Location: University Student Center
Session Chair: Nick Parson, Rio Tinto Alcan 2:00 PM Effect of Si and Mn Additions on Solid Solution Hardening of Aluminum Alloys: Qinglong Zhao1; Bjørn Holmedal1; 1Norwegian University of Science and Technology Non-heat-treatable aluminum alloys owe their strength mainly to elements in solid solution, and they usually contain more than two elements in solid solution. But the combination effect of multiple elements on strength is not well known. Small amount of Si usually exists in many commercial alloys. A weak solid solution hardening of Si is predicted theoretically by Leyson et al (Nature Mater 2010), but few quantitative evidences are reported. Furthermore, small amounts of Si may affect solid solution hardening of Mn in AA3xxx alloys. A number of commercial purity aluminum alloys (AA1xxx and AA3xxx) are investigated in this work. The varied solute contents are achieved by cast compositions and heat treatments. The strength is measured by tensile tests at room temperature.
13th International Conference on Aluminum Alloys
Technical Program
4:10 PM Modeling of Work-Hardening in an Age-hardenable AA7108 Aluminum Alloy: Ida Westermann1; Odd Sture Hopperstad2; Ole Runar Myhr3; Knut Marthinsen2; Bjørn Holmedal2; 1SINTEF; 2Norwegian University of Science and Technology; 3Hydro Aluminium To understand and predict the mechanical properties of aluminum alloys are of great importance with respect to e.g. strength requirements and forming operations. For heat-treatable alloys, the strength and workhardening behavior is mainly attributed to the presence of hardening precipitates. In this work, a first step has been taken to further develop an already existing two internal state variable work-hardening model that has been previously validated for Al-Mg-Si alloys, to include alloys within the Al-Zn-Mg system. The input parameters are based on quantitative
4:30 PM Overageing Kinetics in Fibrous vs Recrystallised Al-Mg-Si-Cu Alloys: Jostein Røyset1; Jon Holmestad1; Calin Marioara2; 1Hydro Aluminium Research and Technology Development; 2SINTEF Materials and Chemistry The Al-Mg-Si(-Cu) alloys are by far the most applied aluminium alloys for extrusion, due to the favourable combination of extrudability and functional properties. The grain structure may be either recrystallised or fibrous, depending on the alloy composition and processing conditions. In the present work, two essentially similar Al-Mg-Si(-Cu) alloys are made, but with different Mn levels so that in the extruded state one alloy is recrystallised whereas the other is fibrous. Samples of extruded material from each alloy was solution heat treated, aged to maximum hardness at 155°C, and subsequently overaged at 200°C and 250°C for several weeks. The overageing is monitored by Vickers hardness measurements, and for selected times the microstructure is characterized in detail with TEM. The results are discussed and conclusions are drawn in the light of contemporary metallurgical theory.
WEDNESDAY PM
3:30 PM Microstructure and Mechanical Properties of an Al-Mg-Sc-Zr Alloy Subjected to Extensive Cold Rolling: Anna Mogucheva1; Evgeniya Babich1; Rustam Kaibyshev1; 1Belgorod State University Aluminum alloy was subjected to the cold rolling at strains ranging from 20 to 80%. Microstructures of the rolled sheets were studied by electron backscattered diffraction method (EBSD), transmission electron microscopy (TEM); and then tensile tests were carried out to investigate the relationship between mechanical properties and microstructural parameters that include grain size and texture distribution. The grains in the rolled sheets were effectively refined during rolling; and the texture intensity increased with increasing the rolling reduction. The strain hardening upon the cold rolling resulted in the significant enhancement of mechanical properties. It was shown by using the tensile specimens cut along the rolling direction that cold rolling with a total reduction of 20% led to the 30% increase in yield stress (YS); after 80% reduction the 62% increase in YS in comparison with initial material took place.
experimental TEM investigations of the precipitate distributions in an AA7108 aluminum alloy heat treated to different tempers. The model has been calibrated, implemented and validated with respect to data obtained by tension and compression tests. The work-hardening model shows promising results, and yields reasonable agreement between model predictions and experimental results.
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