Influence of the extrusion parameters on the microstructure and propertiesof an Al-Si alloy

The influence of the extrusion temperature and the extrusion speed on the m icrostructure, the texture and the residual stresses in AlSi25Cu4Mg1 after indirect extrusion has been studied using microscopical, X-ray and high-ene rgy synchrotron X-ray methods. The texture of the extrudates depends strong ly on the billet temperature and also is influenced by the speed of extruda tes. The residual stress state in the bulk of the extrudates essentially is determined by temperature gradients across the diameter and differences in the thermal expansion of the aluminium matrix and the silicon particles. T he extrudates processed with a billet temperature of 450 degreesC have a hi gher strength and lower formability than the extrudates processed with a bi llet temperature of 300 degreesC, which is not a texture effect but due to a finer precipitate size in the aluminium matrix.