Effect of Temperature and Revolution on the Microstructure, Texture and Microhardness of the AZ80 Alloy Cup Prepared by Rotating Backward Extrusion

Microstructure evolution, phase development and mechanical property of AZ80 alloy cup with various processing temperatures (573 K, 613 K, 653 K) and rotating revolutions (N = 0, 5, 50, 100) during rotating backward extrusion (RBE) were explored. The study founded that reducing deformation temperature or increasing revolution could promote the grain refinement and DRX proportion. And the sample deformed at the condition of 573 K and N = 100 exhibited the best grain refinement effect (grain size was 2.5 mu m, DRX ratio was up to 99.01%). The bulk eutectic phase existed at all deformation temperatures, while the dynamic precipitation was only precipitated at temperature of 573 K and 613 K. Increasing the deformation temperature or revolution could reduce the proportion of the second phase. And an increase in revolution or a reduction of temperature would reduce the average size of second phase, due to the phase could be broken by large strain and resolved with elevated temperature. Moreover, increasing the revolution and deformation temperature could promote the texture weakening, which would be contributed to the occurrence of new recrystallization grains with random orientation and the activation of non-basal slip system. The mechanical property of microhardness was significantly improved with rotating revolution increasing and deformation temperature decreasing. Supported by the grain refinement and dispersion strengthening, the sample deformed at condition of 573 K and N = 100 achieved maximum hardness values of 96.3 HV.