Enhancement of Room Temperature Stretch Formability of Mg–1.5 mass%Mn Alloy by Texture Control

Abstract

Mg1.5 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 773813 K and subsequent warm-rolling at temperatures of 373523 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.

Enhanced Room-Temperature Stretch Formability of Mg–0.2 mass%Ce Alloy Sheets Processed by Combination of High-Temperature Pre-Annealing and Warm Rolling

“…At first glance, it seems that the lower texture intensity and larger inclination angle of the basal pole of sheet A contributed to strain in the thickness direction, resulting in enhanced room-temperature formability. On the other hand, our previous studies suggested that a reduction in basal texture intensity of 23 is essential for significant enhancement of the room-temperature formability of Mg alloys [MgMn alloys 11) and AZ31 alloys 13) ]. The above information implies that in addition to the variation in basal texture, an additional microstructural factor was likely to have affected the room-temperature formability in the case of MgCe alloy sheets.…”

“…The above rolling procedure is considered to promote extensive twinning, which contributes to the suppression of basal texture formation. 11) These results obtained for MgMn alloys suggest that the above rolling procedure might also be effective for MgCe alloys.…”

Development of Room Temperature Formability of Rolled Magnesium Alloy Sheets by Texture Control

“…In the specimen A, the pre-annealing, rolling and final annealing temperature was set to 500, 150 and 200℃ , respectively. In the specimen B, the pre-annealing, rolling and final annealing temperature was set to 500, 500 and 300℃ , respectively 37) .…”