Assessment of the forging conditions of 6061/Al2O3/10p using processing maps and stability criteria

The power dissipation efficiency contours and the stable and unstable plastic flow regions as a function of temperature and strain rate are developed for 6061/Al2O3/10p composite. An unstable region is apparent at low strain rates (0.001-0.025 s(-1)) and high temperatures (430-500 degrees C); such zone can be attributed to the diffusional void growth and to the formation of wedge cracks at the grain boundary triple junctions. In the stable plastic flow region, the trend of the isoefficiency lines reveals that the same power dissipation efficiency levels can be obtained both at low temperatures and low strain rates and at high temperatures and high strain rates. Moreover, higher power dissipation efficiency values appear at higher temperatures. The most favourable forming window is defined by the temperature and strain rate ranges of 450-500 degrees C and 0.03-0.3 s(-1). Such processing window can be properly used for the definition of the optimum forging parameters.