Enhancement of room temperature stretch formability of Mg-1.5 mass%Mn alloy by texture control

Abstract

Mg-1.5 mass%Mn (M1) alloy is known for its high damping properties. In this study, effects of process parameters such as rolling and annealing temperatures on the texture formation in rolled M1 alloys were investigated for the purpose of enhancing their room-temperature formability. Specimens were pre-annealed, warm-rolled and then finally annealed. Pre-annealing at temperatures of 773-813K and subsequent warm-rolling at temperatures of 373-523 K resulted in the formation of basal textures with low intensities. The (0002) pole was inclined towards the rolling direction. The specimens annealed at 473 K in the final step showed a high Erichsen value of 7.9, while the values for specimens annealed at temperatures higher than 623 K were lower. This deterioration in the Erichsen values was attributed to the occurrence of abnormal grain growth accompanied by recrystallization. It is suggested that iterating the protocol involving pre-annealing at high temperatures and the subsequent warm-rolling promoted the formation of extensive twinning, which contributed to the formation of basal textures with low intensities. The internal friction of the M1 alloy sheets was found to be 70% of that of pure Mg. © 2013 The Japan Institute of Metals.