Secondary precipitation during homogenization of Al-Mg-Si alloys: Influence on high temperature flow stress
| Autor: | Johannes A. Österreicher, Andreas Schiffl, Gilles R. Bourret, Manoj Kumar, Sabine Schwarz |
|---|---|
| Rok vydání: | 2017 |
| Předmět: |
Materials science
Precipitation (chemistry) 020502 materials Mechanical Engineering Metallurgy 02 engineering and technology Flow stress 021001 nanoscience & nanotechnology Condensed Matter Physics Microstructure Homogenization (chemistry) 0205 materials engineering Mechanics of Materials visual_art Aluminium alloy visual_art.visual_art_medium Formability General Materials Science Extrusion Dilatometer 0210 nano-technology |
| Zdroj: | Materials Science and Engineering: A. 687:175-180 |
| ISSN: | 0921-5093 |
| Popis: | In the automotive industry Al-Mg-Si alloys are often chosen for high strength extruded profiles. However, the production of such profiles can be challenging for high alloy contents. Among several processing steps, the homogenization heat treatment before extrusion is readily accessible to modifications to improve high temperature formability. In this work, the influence of five different homogenization variants on the flow stress of AA6082 at elevated temperatures was assessed by compression testing in a deformation dilatometer at 450 °C, 480 °C, and 510 °C. The observed differences in flow stress were interpreted with regards to the microstructure. Samples from billets homogenized at higher soak temperatures exhibited lower hot flow stresses in subsequent dilatometer testing, indicating better processability. Since the decrease in flow stress is approximately constant at all test temperatures, it is suggested that it is due to a lower number density of relatively temperature-stable α-Al(Mn,Fe)Si dispersoids formed during homogenization at higher temperatures; these dispersoids are stable at all three test temperatures. In contrast, the influence of a cooling rate variation was relatively minor and diminishes at higher test temperatures since Mg-Si precipitates – whose size and number density is affected by changes of the cooling rate – are less stable at the higher test temperatures. |
| Databáze: | OpenAIRE |
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