Microstructure effects on the forgeability of Zn-22Al eutectoid alloy

The forgeability of Zn-22Al eutectoid alloy with two types of microstructure has been studied by using a Gleeble simulation machine. Experimental results showed that the fine-grained Zn-22Al 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-22Al eutectoid alloy were drastically higher than that of fine-grained Zn-22Al eutectoid alloy tested in the same forging conditions. The stress-softening phenomenon and oscillatory behavior exhibited in these stress-strain curves of lamellar Zn-22Al eutectoid alloy may be attributed to the dynamic recovery (and/or recrystallization) effect at elevated temperatures.