scholarly journals Microstructure Evolution and Grain Growth Model of AZ31 Magnesium Alloy under Condition of Isothermal

2015 ◽  
Vol 2015 ◽  
pp. 1-6
Author(s):  
Zhongtang Wang ◽  
Lingyi Wang ◽  
Lizhi Liu
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Growth Model ◽  
Microstructure Evolution ◽  
Heating Temperature ◽  
Holding Time ◽  
Az31 Magnesium Alloy ◽  
Temperature Range ◽  
Grain Growth Model

Microstructure evolution of AZ31 magnesium alloy in annealing process had been investigated by experiment study at heating temperature range of 150°C–450°C and holding time range of 15 min–60 min. The effects of heating temperature and holding time on grain growth had been analyzed. The results presented that the grain size tends to grow up with the increase of holding time at a certain temperature. At a certain holding time, the grain size increased firstly and then decreased at the heating temperature range of 150–250°C. And when heating temperature is higher than 250°C, the grain grows up gradually with the increase of heating temperature. The grain growth model of AZ31 Mg alloy has been established by regression based on the experimental data at temperature of 250–450°C, and the relative error between model calculation results and experimental results is less than 19.07%. Activation energy of grain growth of AZ31 magnesium alloy had been determined.

Refinement Effect and Mechanism of AZ31 Magnesium Alloy by Electromagnetic Stirring under the Effect of Grain-Refiner

2013 ◽  
Vol 631-632 ◽  
pp. 556-561 ◽  
Author(s):  
Sheng Yuan Gao ◽  
Shi Lian Qu ◽  
Yue Yuan ◽  
Bao Qin Fu
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Heterogeneous Nucleation ◽  
Holding Time ◽  
Electromagnetic Stirring ◽  
Az31 Magnesium Alloy ◽  
Grain Refiner ◽  
Nucleation Sites ◽  
Continuously Cast ◽  
Refinement Effect

The effects of electromagnetic stirring and Al4C3grain refiner on the grain refinement of semi-continuously cast AZ31 magnesium alloy were discussed in this investigation. The results indicate that electromagnetic stirring has effective refining effect on the grain size of AZ31 magnesium alloy under the effect of Al4C3grain refiner. Electromagnetic stirring can “activate” the Al4C3particles, resulting in more heterogeneous nucleation sites for the primary α-Mg grains. But, longer holding time can “inactivate” the Al4C3particles, and the optimal experimental holding time is 60 min in the present investigation. The activated rate of the electromagnetic under the experimental condition ρ2=1.65%.

Microstructure Stability of a Fine-Grained AZ31 Magnesium Alloy Processed by Constrained Groove Pressing During Isothermal Annealing

2017 ◽  
Vol 139 (8) ◽  
Author(s):  
Kai Soon Fong ◽  
Ming Jen Tan ◽  
Fern Lan Ng ◽  
Atsushi Danno ◽  
Beng Wah Chua
Keyword(s):  
Activation Energy ◽  
Grain Size ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Isothermal Annealing ◽  
Az31 Magnesium Alloy ◽  
Growth Equation ◽  
Alloy Plate ◽  
Microstructure Stability ◽  
Average Grain Size

In this study, an AZ31 magnesium alloy plate was processed by constrained groove pressing (CGP) under three deformation cycles at temperatures from 503 to 448 K. The process resulted in a homogeneous fine grain microstructure with an average grain size of 1.8 μm. The as-processed microstructure contained a high fraction of low-angle grain boundaries (LAGB) of subgrains and dislocation boundaries that remained in the structure due to incomplete dynamic recovery and recrystallization. The material's yield strength was found to have increased from 175 to 242 MPa and with a significant weakening of its initial basal texture. The microstructure stability of the CGP-processed material was further investigated by isothermal annealing at temperature from 473 to 623 K and for different time. Abnormal grain growth was observed at 623 K, and this was associated with an increased in nonbasal grains at the expense of basal grains. The effect of annealing temperature and time on the grain growth kinetics was interpreted by using the grain growth equation,  Dn+D0n=kt, and Arrhenius equation, k=k0 exp (−(Q/RT)). The activation energy (Q) was estimated to be 27.8 kJ/mol which was significantly lower than the activation energy for lattice self-diffusion (QL = 135 kJ/mol) and grain boundary diffusion (Qgb = 92 kJ/mol) in pure magnesium. The result shows that grain growth is rapid but average grain size still remained smaller than the as-received material, especially at the shorter annealing time.

Effects of Annealing Parameters on Recrystallization of AZ31 Magnesium Alloy Processed by Continuous Rheo-Extrusion

2011 ◽  
Vol 239-242 ◽  
pp. 15-20
Author(s):  
Ren Guo Guan ◽  
Zhan Yong Zhao ◽  
Fu Rong Cao ◽  
Hong Qian Huang ◽  
Chun Guang Dai ◽  
...  
Keyword(s):  
Growth Rate ◽  
Magnesium Alloy ◽  
Grain Growth ◽  
Annealing Temperature ◽  
Holding Time ◽  
Az31 Magnesium Alloy ◽  
Dislocation Densities ◽  
Recrystallized Grain Size ◽  
Lower Temperature ◽  
Time Required

AZ31 magnesium alloy profiles were prepared by continuous rheo-extrusion, and effects of annealing temperature and time on recrystallization of AZ31 magnesium alloy were investigated. The results reveal that when the profile is annealed in the temperature range from 200°C to 300°C, the moving velocity of grain interface with different dislocation densities on both sides increases with increasing annealing temperature, which is favorable to the formation of crystallized nucleus in the region in which interface sweeps over. As a result, the time required by the accomplishment of recrystallization becomes short. After recrystallization finishes, continuous temperature rise or prolonged holding time result in grain growth. When the profile is annealed at elevated temperature, with the prolongation of holding time, the grain growth rate accelerates obviously, and hence recrystallized microstructure becomes coarse. When the profile is annealed at lower temperature, the grain growth rate becomes small, and the time required by the accomplishment of recrystallization is long, but recrystallized microstructure is fine and homogeneous. When the profile is annealed at 250°C for 4h, average recrystallized grain size is 15μm.

An Object-Oriented Framework for Mesoscopic Modeling of Microstructure Evolution in Materials Processing

2003 ◽  
Author(s):  
Qiang Yu ◽  
Sven K. Esche
Keyword(s):  
Material Processing ◽  
Grain Growth ◽  
Growth Model ◽  
Microstructure Evolution ◽  
Object Oriented ◽  
General Purpose ◽  
Materials Processing ◽  
Simulation Framework ◽  
Mesoscopic Modeling ◽  
Grain Growth Model

This paper addresses the design of a general-purpose, object-oriented simulation framework for mesoscopic modeling of microstructure evolution in material processing. Some new results obtained using a grain growth model, which was incorporated into this framework, are presented.

scholarly journals Microstructure Evolution and Mechanical Properties of AZ31 Magnesium Alloy Sheets Prepared by Low-Speed Extrusion with Different Temperature

Crystals ◽  
2020 ◽  
Vol 10 (8) ◽  
pp. 644
Author(s):  
Wenyan Zhang ◽  
Hua Zhang ◽  
Lifei Wang ◽  
Jianfeng Fan ◽  
Xia Li ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Tensile Strength ◽  
Magnesium Alloy ◽  
Yield Strength ◽  
Magnesium Alloys ◽  
Microstructure Evolution ◽  
Extrusion Temperature ◽  
Az31 Magnesium Alloy ◽  
Low Speed

AZ31 magnesium alloy sheets were prepared by low-speed extrusion at different temperatures, i.e., 350 °C, 400 °C, and 450 °C. The microstructure evolution and mechanical properties of extruded AZ31 magnesium alloy sheets were studied. Results indicate that the low-speed extrusion obviously improved the microstructure of magnesium alloys. As the extrusion temperature decreased, the grain size for the produced AZ31 magnesium alloy sheets decreased, and the (0001) basal texture intensity of the extruded sheets increased. The yield strength and tensile strength of the extruded sheets greatly increased as the extrusion temperature decreased. The AZ31 magnesium alloy sheet prepared by low-speed extrusion at 350 °C exhibited the finest grain size and the best mechanical properties. The average grain size, yield strength, tensile strength, and elongation of the extruded sheet prepared by low-speed extrusion at 350 °C were ~2.7 μm, ~226 MPa, ~353 MPa, and ~16.7%, respectively. These properties indicate the excellent mechanical properties of the extruded sheets prepared by low-speed extrusion. The grain refinement effect and mechanical properties of the extruded sheets produced in this work were obviously superior to those of magnesium alloys prepared using traditional extrusion or rolling methods reported in other related studies.

scholarly journals Grain Growth of AZ31 Magnesium Alloy Based on Three-Dimensional Cellular Automata

2020 ◽  
Vol 2020 ◽  
pp. 1-11
Author(s):  
Yanfeng Li ◽  
Cuirong Liu ◽  
Zhibing Chu ◽  
Wei Li ◽  
Zhisheng Wu ◽  
...  
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Cellular Automata ◽  
Grain Growth ◽  
Minimum Energy ◽  
Three Dimensional ◽  
Az31 Magnesium Alloy ◽  
Two Dimensional ◽  
Heat Preservation ◽  
Grain Diameter

Based on the thermodynamic conversion mechanism and energy transition principle, a three-dimensional cellular automata model of grain growth is established from the aspects of grain orientation, grain size distribution, grain growth kinetics, and grain topology. Also, the effect of temperature on the three-dimensional grain growth process of AZ31 magnesium alloy is analyzed. The results show that the normal growth of three-dimensional grains satisfies the Aboav-weaire equation, the average number of grain planes is between 12 and 14 at 420°C and 2000 CAS, and the maximum number of grain planes is more than 40. Grains of different sizes are distributed normally at different times, most of which are grains with the ratio of grain diameter to average grain diameter R/Rm ≈ 1.0, which meets the minimum energy criterion of grain evolution. The grain of AZ31 magnesium alloy increases in size with the increase of temperature, and the number of grains decreases with the increase in time. The angle between the two-dimensional slices of three-dimensional grains is approximately 120°, which is consistent with that of the traditional two-dimensional cellular automata. The relative error of grain size before and after heat preservation is in the range of 0.1–0.6 μm, which indicates that the 3D cellular automata can accurately simulate the heat preservation process of AZ31 magnesium alloy.

Research on the Ceramic Sintering Grain Growth Model

2016 ◽  
Vol 852 ◽  
pp. 374-377
Author(s):  
Shui Qing Xiao ◽  
Shang Hua Wu
Keyword(s):  
Mechanical Properties ◽  
Grain Size ◽  
Grain Growth ◽  
Growth Model ◽  
Solid Phase ◽  
Ceramic Materials ◽  
Liquid Phase Sintering ◽  
Grain Growth Model ◽  
Ceramic Sintering ◽  
Material Grain Size

Mechanical properties of ceramic materials are closely related to the grain size, and control the ceramic material grain size is the key to increase mechanical properties of materials. Study on the theory of ceramic sintering grain growth model, such as solid phase sintering, liquid phase sintering and master sintering curve (MSC) and so on. Grain growth model not only can be used to guide the actual production design, but also can be used as a computer simulation tools. It is suggest that before use any grain growth model must modify their express from traditional model, and check the equation is correct that it is agree with the result of re-experiment.

Influnce of Grain Size on Dynamic Recrystallization of AZ31 Magnesium Alloy Rolling Sheet

2013 ◽  
Vol 395-396 ◽  
pp. 218-222 ◽  
Author(s):  
Chen Yang Xu ◽  
Fu Xiang Chu ◽  
Xiao Ling Xu ◽  
Hao Chen ◽  
Fang Gao
Keyword(s):  
Grain Size ◽  
Magnesium Alloy ◽  
Dynamic Recrystallization ◽  
Strain Rate ◽  
Microstructure Evolution ◽  
Deformation Temperature ◽  
Az31 Magnesium Alloy ◽  
Deformation Condition ◽  
Evolution Characteristics ◽  
C 30

Microstructure evolution characteristics and the influence of the intial grain size on the dynamic recrystallization of AZ31 were investigated by rolling at deformation temperature of 280 °C, 30% reduction and strain rate of 5.6s-1. The results indicate that under the present deformation condition, when the grain size is 6.2μm the dynamic recrystallization does not occur , twinning dynamic recrystallization (TDRX) occurs when the original grain size are of 7.9μm and 12.7μm, when the original grain size is 21.1μm rotating dynamic recrystallization (RDRX) occurs.

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