The Variation of the workability of aluminium alloys homogenised ingot depend on position

Manufacturing conditions in which the optimum workability is maintained has a significant effect for manufacturing industry. In such processes, large deformation processes under low stresses are required to achieve without crack initiation. The workability of an ingot depends on the chemical composition, microstructure and the heat treatment applied before. The differences in mechanical and structural properties cause the change of the workability between the surface and the center. In this study, it was aimed to have a uniform workability of the ingot by applying homogenisation treatments in different conditions in order to reduce the workability difference of the surface and the center after the direct casting of the ingot. The mechanical and structural properties of 200 mm diameter of aluminium alloys ingots that were not subjected to any treatment after casted directly into the mould were determined by means of torsion test, hardness test, metal microscope, SEM, EDS and X-ray difractometer. The hot torsion tests carried out after homogenisation treatment were conducted at different deformation temperatures with the deformation speed of 2.10' s"1. After the torsion tests, it was observed for 2014 and 6063 Al ingots that while the stresses declined from the surface towards the center, the strain increased, and there was a difference in the value of the stresses and strain between the surface and the center. That difference between the surface and the center reduced with homogenisation treatment. The best distribution between the surface and the center in 2014 Al and 6063 Al alloys were obtained at the deformation at the temperature of 440 °C for the ingots cooled in the furnace after the homogenisation at 510 °C and 540 °C, respectively. In addition, it was observed that the deformation temperature has a significant impact on stress and strain curves. It was also observed that the stress decreased while the strain increased with the increase of the deformation temperature. It was determined that the stress and strain differences in the regions decreased slightly. 2002, 169 pages Key Words : Hot Workability, hot torsion, homogenisation, deformation, aluminium alloys 11