Forging of the AA6061/23 vol.%Al2O3p composite: Effects on microstructure and tensile properties

In this study, the influence of the forging process on microstructure, tensile resistance and fracture behaviour of the AA6061/Al2O3/23p composite is presented and discussed. Forging was carried out in an open die, at the temperature of 470 °C, with a deformation ratio of 2.5:1 then the specimens were heat treated at the T6 condition. Microstructural characterization and density measurements showed that hot forging did not induce crack of the particle on the AA6061/Al2O3/23p composite and reduced the porosity with respect to the as-cast material. Usually in literature a reduction of the degree of clustering, due to plastic deformation, is reported. On the contrary, probably due to the low deformation ratio applied, no appreciable difference was observed in the degree of particles clustering, before and after forging. The concurrent effect of plastic deformation and high temperature during forging, instead, led to a recrystallization of the aluminium alloy matrix, with a consequent grain refinement. These microstructural modifications induced an improvement in the tensile strength and an increase, from 50% at room temperature to 165% at 300 °C, of elongation at failure in the forged composite.