In this diploma thesis, we investigated the effect of cooling rate after homogenization annealing on the hot-deformation behaviour of the EN AW-6110A aluminium alloy. The initial as-cast condition was compared with three homogenized conditions subjected to different cooling rates. The cooling rate was varied by applying turbo fan cooling, slow air cooling, and water-spray cooling. Two specimens were prepared from each homogenized condition. Hot-deformation tests were carried out using a Gleeble 3500 thermomechanical simulator at two temperatures, 390 and 440 °C. These temperatures represent the lowest and highest material temperatures during industrial extrusion. After hot-deformation testing, the specimens were longitudinally sectioned, metallographically prepared, and examined using an optical light microscope.
At both deformation temperatures, the specimen in the initial as-cast condition exhibited the highest flow stress. At 390 °C, the maximum flow stress was approximately 129 MPa, whereas at 440 °C it was approximately 108 MPa. Among the homogenized conditions, the lowest maximum flow stress at 390 °C was measured for the specimen subjected to slow air cooling and was approximately 88 MPa. At 440 °C, the lowest value was measured for the water-spray-cooled specimen and was approximately 72 MPa. Differences between the individual conditions were also observed in the optical micrographs. Since the type and fraction of secondary phases were not determined, their influence on the measured flow stresses could not be directly confirmed. Only one compression test was performed for each condition; therefore, the results were not statistically evaluated and were treated primarily as comparative results.
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