Mechanical properties and deep drawability of Mg-Gd-Y-Zr alloy rolling sheet at elevated temperatures

Mechanical properties and deep drawability of Mg-Gd-Y-Zr alloy rolling sheet were systematically studied. For this purpose, uniaxial tensile tests were conducted to investigate mechanical properties, strain rate sensitivity parameter (m-value) and plastic strain ratio (R-value) of the sheet at elevated temperatures. The sheet exhibited a high strength at 513 K and superplasticity above 623 K. The m-value and R-value ranged from 0.07 to 0.32 and 0.9 to 1.4, respectively. Non-isothermal deep drawing experiments were performed to explore the influence of technical parameters on deep drawability. For comparison purpose, traditional AZ31 sheet was chosen for testing on the same device. Limiting drawing ratio (LDR) of Mg-Gd-Y-Zr sheet reached >5.2 that was much higher than that of AZ31 sheet. Textures of the initial sheet and the necking regions for post-deforming cylindrical cups were measured. It is suggested from texture analysis that the activation of pyramidal slip system accounted for the locally necking of the cup-wall. The excellent drawability of Mg-Gd-Y-Zr sheet was attributable to its relatively stronger temperature sensitivity of flow stress and was not connected with an exceptional R-value or m-value.