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A Study on the Tensile Deformation and Fracture Behaviors of As-extruded Magnesium Alloys

Author: YanZuoZuo
Tutor: ZhangHui
School: Hunan University
Course: Materials Processing Engineering
Keywords: Extruded magnesium alloy Heat treatment Continuous extrusion Tensile deformation Fracture
CLC: TG115.5
Type: Master's thesis
Year: 2007
Downloads: 543
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Abstract


Magnesium alloy is the practical application of the lightest structural metal materials with high specific stiffness and specific strength, good electromagnetic shielding, damping properties and thermal performance, with a wide range of applications in the aerospace, automotive industry and the field of 3C products prospects. Cast magnesium alloy product usage greater than wrought magnesium alloy products with better mechanical properties, but the deformation after extrusion, forging, rolling craft production products, which meet the needs of a more diverse structural parts. However, the organization of wrought magnesium alloy, mechanical properties and fracture behavior of a lack of systematic study, limiting the further development of the wrought magnesium alloy. In this paper, X-ray diffraction and mechanical performance analysis, scanning electron microscopy and other analytical tools, a more systematic study extrusion of AZ91 Microstructure of ZK60, AZ31 magnesium alloy microstructure evolution under different conditions, the tensile deformation behavior and metallographic observation fracture mechanism. The main research content and results are as follows: (1) to study the effect of heat treatment on the tensile deformation and fracture behavior of extruded AZ91 and ZK60 magnesium alloy The results show that: compared to the tensile strength of AZ91 alloy solid solution state and squeezed state does not change but elongation greatly increased; the aging hardness peak tensile strength compared to the solid solution state have improved to some extent, but there was a substantial reduction in elongation. ZK60 alloy different solute state and extruded state compared to the tensile strength and elongation reduced a considerable extent, and the the aging hardness peak tensile strength when compared to the solute state some improvement, but the extension long rates have reduced significantly. AZ91 alloy after solution treatment, grain size compared to the extruded state somewhat increased, but the grain size after the ZK60 alloy solution treatment significantly roughened. Two alloys aging treatment accompanied by strengthening phase precipitation. The two alloys fracture squeezed state and solution state has a dimple characteristics, for pore nucleation toughness fracture mechanism. Fracture of AZ91 aging peak state showing a mixture of toughness and fragility fracture characteristics the aging peak state ZK60 fracture solvability the rationale rivers and cleavage stairs, showing a characteristic of brittle cleavage fracture. (2) the application of magnesium alloy, the room temperature plastic processing capacity was very limited, preparation of ultra-fine grain structure (micro) is an effective method for high elongation and superplastic materials. This article was prepared using a continuous extrusion method fine grain AZ31 magnesium alloys were studied, the results showed that: a continuous extrusion can effectively refine AZ31 alloy grains and a change in grain orientation, resulting in material elongation has been greatly improved. Fracture the AZ31 alloy conventional extrusion state showing toughness mixed with brittle fracture characteristics, and the the continuous extrusion state of fracture dimple characteristics, for pore nucleation toughness fracture mechanism. (3) In addition, this paper studies the jet the deposition FVS0812 resistant aluminum alloy sheet at a temperature of 250 ~ 450 ℃, strain rate of 0.001 ~ 0.1s-1 under tensile deformation and fracture behavior. The results showed that fine crystal material: As the spray deposition system a higher dynamic recovery, elongation is not only increases as the temperature increases, also increase as the strain rate increases, with the conventional aluminum The variation of the alloy sheet opposite.

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CLC: > Industrial Technology > Metallurgy and Metal Craft > Metallurgy and Heat Treatment > Metallurgy ( Physical Metallurgy ) > Analytical tests of the metal (Metal Testing and Materials ) > Mechanical properties ( mechanical properties ) test
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