Dissertation > Excellent graduate degree dissertation topics show

Organization Uniformization Extrusion and Microstructure Evolution Simulation of Casting AZ91D Magnesium Alloy

Author: LiCaiJie
Tutor: LiHongBo
School: Yanshan University
Course: Materials Processing Engineering
Keywords: Magnesium alloy Finite element simulation Rheological stress Microstructure evolution Extruding
CLC: TG146.22
Type: Master's thesis
Year: 2008
Downloads: 254
Quote: 3
Read: Download Dissertation

Abstract


The purpose of this paper is to examine the uniaxial compression behavior, extruding in the reversed temperature field and the microstructure evolution in the deformation of casting AZ91D Mg alloy under different conditions, and to determine the optimum process conditions for the best deformation properties of this alloy, thus supplying a reliable basis for the development and application for the deformation technology of Mg alloy.Uniaxial compression tests were carried out at the temperature range 250~450℃and the strain rate of 0.0015s-1, 0.015s-1, 0.15s-1 to evaluate the uniaxial compression behavior of casting AZ91D Mg alloy. The influence of deformation temperature, strain rate and strain to the rheological stress under compression was analyzed. Considering the effect of recrystallize-emollience during thermal deformation, the rheological stress mathematic model including the emollience factor which is fit for AZ91D Mg alloy was put forward. The microstructure of specimens were observed by optical microscopy. It is demonstrated that the initial grain size of casting AZ91D Mg alloy is 40μm. The continuous dynamic recrystallization occurred when the deformation temperature is 300℃, 350℃and the strain rate is 1.5×10-3s-1. The dynamic recrystallization is mostly in the grain boundary. When the deformation temperature is 400℃and the strain rate is 1.5×10-3s-1 the dynamic recrystallization occurred altogether. The microstructure is homogeneous large angle boundary equiaxed grain and the grain size is 8~10μm. There is no crack in the surface of specimen so this is the best condition for the deformation. The recrystal grain size gradually reduced with the strain rate improved and the temperature reduced.With Yada model which is amended, a finite element soft ware called SuperForm was used to analyze microstructure evolution in the deformation of AZ91D Mg alloy. The results show that the simulation of microstructure evolution of the uniaxial compression and the experiment results are anastomotic.The extruding experiment of AZ91D Mg alloy was carried out at the temperature range 300~400℃under the reversed temperature. The extruding ratio are 4:1 and 9:1. The microstructure of extruding specimens was observed by optical microscopy. The experiment results indicated that the microstructure was more homogeneous when the temperature contrast between die and specimens was 100℃. The microstructure was homogeneous equiaxed grain which was 8μm when the die and the specimen was 400℃and 300℃and the extruding ratio was 9:1. This is the best condition for extruding.

Related Dissertations

  1. Microstructure and Mechanical Properties of Mg-Zn-Y-Zr Alloys,TG146.22
  2. The Large Concrete Hydration Heat Temperature Effects Research of the Cable Stayed Bridge,U441.5
  3. The Research on Extrusion Parameters Through the Plate Billet of Magnesium Alloy,TG379
  4. The Research on Rolling and Heat Treatment Technology of AZ31 Magnesium Alloy Thin Sheet,TG166.4
  5. New Grain Refiners and Their Refining Behaviors of AZ31 Magnesium Alloy,TG146.22
  6. The Research of Complex Surface Numerical Value Simulation and Polishing Technology.,TG580.692
  7. Study on Stamping-forging Process and Experiment of Sheet Metal Parts with Non-uniform Thickness,TG386
  8. Rolled Mg-Zn-Ce-Zr (Mn) alloy microstructure and mechanical properties of,TG339
  9. Repeated upsetting suppress Mg-Si alloys prepared microstructure and properties,TG146.22
  10. Dissimilar magnesium alloy AZ31 and NZ30K study of laser welding,TG456.7
  11. Pipeline circumferential excitation calculation method of magnetic flux leakage,TG115.284
  12. Metal plate surface electromagnetic ultrasonic flaw detection technology research,TG115.284
  13. ECAP for Mg-Zn-Zr-Gd alloy fatigue behavior of,TG379
  14. Longitudinal magnesium alloy AZ91 under AC magnetic field properties of welded joints,TG407
  15. Magnesium alloys and corrosion resistance of phosphating process,TG174.4
  16. Plastic deformation on direct smelting crude magnesium AZ91 magnesium alloy and hardness of,TG146.22
  17. Die-cast magnesium alloy automotive steering column bracket CAE,TG249.2
  18. Vacuum casting AZ91 Magnesium Alloy Corrosion Resistance,TG146.22
  19. Mg-Sn alloy microstructure and mechanical properties,TG146.22
  20. Compression at room temperature direct smelting crude magnesium AZ91 magnesium alloy hardening and annealing transformation kinetics,TF822
  21. Pipeline magnetic flux leakage detection signal reconstruction technology within,TN911.23

CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallic materials > Non - ferrous metals and their alloys > Light non-ferrous metals and their alloys > Magnesium
© 2012 www.DissertationTopic.Net  Mobile