Texture and crystal plasticity in AA3XXX aluminium alloys
- Reference number
- SM11-0015
- Start and end dates
- 120101-141231
- Amount granted
- 703 841 SEK
- Administrative organization
- Gränges AB
- Research area
- Materials Science and Technology
Summary
The proposed project shall increase our understanding of the microstructural deformation mechanisms in soft, thin, and large-grained aluminium sheet material. A practical calculation method for the texture development and anisotropic mechanical properties shall be established as well. The project shall also initiate a long and fruitful co-operation between Sapa and Linköping University, it shall raise the competence level on texture and crystal plasticity at Sapa, and it shall initiate a new wave of aluminium related research at Linköping University. The proposed work consists of experimental investigations of texture evolution and plastic deformation with the advanced scanning electron microscope at the division of Engineering Materials, and of corresponding computer simulations. The experiments shall be performed on samples of different thicknesses where the thinnest samples have a grain size that is equal to the sample thickness. For the calculations, a model shall be chosen that only requires moderate computational ressources but still gives results of sufficient accuracy for practical purposes. We expect the following scientific results: 1) Understanding of the role of different texture components and orientations within texture components on mechanical properties of our samples. 2) Good predictive estimates of texture evolutions from known deformation conditions and good predictive estimates of (anisotropic) mechanical properties from texture measurements.
Popular science description
Aluminium alloys used in practical applications are built up of many small grains, of sizes between approximately 1 µm and 1 mm. One grain can be considered as a miniature single crystal, where all atoms are located at the positions given by the crystal structure. Aluminium possesses the face-centered cubic crystal structure. This means that an aluminium single crystal consists of many small cubes accurately ordered side-by-side in all three dimensions and that all atoms occupy positions at the corners of these cubes or in the centres of the cube faces. The grains are separated by grain boundaries, and the 'cubes' in two different grains are usually oriented differently. The orientation of the grains can be completely random, or certain orientations can dominate over other orientations. In the latter case, the material possess a texture. The texture has a significant influence on mechanical properties because it is more easy to deform a grain along one direction than along another one. All rolled and extruded aluminium alloys possess significant textures. In the proposed project, we will investigate in detail how thin, soft, and large-grained aluminium alloy samples deform under a tensile force. In these materials, many grains extend over the complete material thickness. This is an intermediate case between the two limiting cases where the material is either a single crystal or where the grains are small as compared to the dimensions of the sample. The materials described above are needed to build automotive heat exchangers. The Sapa Group produces heat exchanger sheet materials in Finspång, Sweden, and in Shanghai, China, and is the world's largest supplier of these materials. Heat exchanger sheet materials are subjected to forming operations and the final mechanical properties of the materials in the heat exchanger are very important. The division of Engineering Materials owns a special electron microscope which is equipped with a small tensile test stage. In addition, a so-called EBSD detector makes it possible to measure crystal orientations with a high spatial resolution. This microscope therefore offers unique possibilitoes for the proposed project. Besides our mutual interest in the scientific and technical aspects of the project, Sapa Technology and the division of Engineering Materials have a general interest to work together because we expect to increase each other's competence, solve problems together and find innovative solutions.