Microstructure Effects on the Forgeability of Zn-22AI Eutectoid Alloy

The forgeability of Zn-22AI eutectoid alloy with two types of microstructure has been studied by using a Gleeble simulation machine. Experimental results showed that the fine-grained Zn-22AI eutectoid alloy possessed excellent forgeability. The flow stress was only 11.5 MPa at 200 °C in a compressive strain rate of 0.006 s^-1 and then remained constant during the whole forging process. However, the compressive stress-strain curves of lamellar Zn-22AI eutectoid alloy were drastically higher than that of fine-grained Zn-22AI eutectoid alloy tested in the same forging conditions. The stress-softening phenomenon and oscillatory behavior exhibited in these stress-strain curves of lamellar Zn-22AI eutectoid alloy may be attributed to the dynamic recovery (and/or recrystallization) effect at elevated temperatures.