Behaviour of centrifugally cast 208.0 aluminum alloy at different pouring temperatures

This investigation studies effect of pouring temperature on microstructure and segregation of 208.0 aluminum alloy. The samples were cast at three different temperatures 850, 900 and 950°C. Characteristics and distribution of the primary particles were assessed by the optical microscopy (OM), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) and image analyzer software. The hardness along the thickness of samples was measured to investigate the variation in mechanical properties corresponding to the variation in microstructure. The results show that fine equiaxed grains and coarse columnar grains are formed at lower and higher pouring temperatures, respectively. Also as the pouring temperature increases, the rate of nucleation and solidification decreases due to slower heat transfer. In this situation, dendrites grow and dendrite-arm spacing increases. By raising pouring temperature from 850°C to 950°C, amounts of copper at external wall increases. Because the density of copper is higher (8.9 vs. 2.7 g/cm3), therefore copper moves towards the mould external wall due to a higher centrifugal force and intensify segregation

Keywords:

Pouring temperature , Centrifugal casting , Segregation , Microstructure , Al2Cu