scholarly journals Study on the Time-Dependent Mechanical Behavior and Springback of Magnesium Alloy Sheet (AZ31B) in Warm Conditions

Materials ◽  
2021 ◽  
Vol 14 (14) ◽  
pp. 3856
Author(s):  
Jae-Hyeong YU ◽  
Chang-Whan Lee
Keyword(s):  
Magnesium Alloy ◽  
Stress Relaxation ◽  
Dynamic Recrystallization ◽  
Mechanical Behavior ◽  
Alloy Sheet ◽  
Holding Time ◽  
Time Dependent ◽  
Die Set ◽  
Creep And Stress Relaxation ◽  
Springback Angle

In this study, the time-dependent mechanical behavior of the magnesium alloy sheet (AZ31B) was investigated through the creep and stress relaxation tests with respect to the temperature and pre-strain. The microstructure changes during creep and stress relaxation were investigated. As the tensile deformation increased in the material, twinning and dynamic recrystallization occurred, especially after the plastic instability. As a result, AZ31B showed lower resistance to creep and stress relaxation due to dynamic recrystallization. Additionally, time-dependent springback characteristics in the V- and L-bending processes concerning the holding time and different forming conditions were investigated. We analyzed changes of microstructure at each forming temperature and process. The uniaxial tensile creep test was conducted to compare the microstructures in various pre-strain conditions with those at the secondary creep stage. For the bending process, the change of the microstructure after the forming was compared to that with punch holding maintained for 1000 s after forming. Due to recrystallization, with the holding time in the die set of 60 s, the springback angle decreased by nearly 70%. Increased holding time in the die set resulted in a reduced springback angle.

scholarly journals Critical Rolling Process Parameters for Dynamic Recrystallization Behavior of AZ31 Magnesium Alloy Sheets

Materials ◽  
2018 ◽  
Vol 11 (10) ◽  
pp. 2019
Author(s):  
Wenke Wang ◽  
Qing Miao ◽  
Xuemin Chen ◽  
Yang Yu ◽  
Wencong Zhang ◽  
...  
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Process Parameters ◽  
Rolling Direction ◽  
Rolling Process ◽  
Alloy Sheet ◽  
Rolling Temperature ◽  
Az31 Magnesium Alloy ◽  
Texture Intensity ◽  
C 30

In this work, the influence of various rolling temperatures and thickness reductions on the dynamic recrystallization (DRX) behavior of AZ31 magnesium alloy sheets was investigated. Meanwhile, the texture variation controlled by DRX behavior was analyzed. Results suggested that, with the help of DRX behavior, reasonable matching of rolling temperature and thickness reduction could effectively refine the grain size and improve the microstructure homogeneity. Using the grain refinement and microstructure homogeneity as the reference, the critical rolling process parameters were 400 °C—30%, 300 °C—30%, and 250 °C—40% in the present work. In terms of basal texture variation, the occurrence of twins produced the largest maximum texture intensity. However, for the sheets with DRX behavior, the maximum texture intensity decreased sharply, but would steadily increase with the growth of DRXed grain. Additionally, for DRXed grains, the <11-20>//RD (RD: rolling direction) grains would gradually annex the <10-10>//RD grains with the growth of DRXed grains, which finally made their texture component become the dominant texture state. However, when the deformation continued, the <10-10> in DRXed grains would rotate toward the RD again. Weighted by the fracture elongation of AZ31 magnesium alloy sheet, the critical thickness reductions were 30–40% under the rolling temperature of 400 °C.

scholarly journals Dynamic Recrystallization and Grain Growth in a ZK60 Magnesium Alloy Sheet Produced by Isothermal Rolling

2004 ◽  
Vol 467-470 ◽  
pp. 1175-1180 ◽  
Author(s):  
Arthur Galiyev ◽  
Rustam Kaibyshev
Keyword(s):  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Grain Refinement ◽  
Grain Growth ◽  
Alloy Sheet ◽  
Ultrafine Grained ◽  
Zk60 Alloy ◽  
Higher Temperature ◽  
Superplastic Properties ◽  
Zk60 Magnesium Alloy

A ZK60 magnesium alloy was subjected to isothermal rolling (IR) at 275 and 300°C. This processing resulted in grain refinement through dynamic recrystallization (DRX) at both temperatures. The recrystallized volume fractions of 82 and 95% and average sizes of fine grains of 2.5 and 3.7 µm were achieved after IR at 275 and 300°C, respectively. It was shown that the ultrafine-grained structure produced by DRX at 300°C exhibited higher stability under following static and dynamic annealing than that produced at 275°C. This fact was attributed with the formation of a less constrained DRX structure at higher temperature of IR. As a result, the sheet produced from the ZK60 alloy at 300°C showed superior superplastic properties. Conversely, it was not feasible to enhance the superplastic properties in the ultrafine-grained alloy produced at 275°C because significant grain growth occurred during further processing of the as-rolled alloy.

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