Evaluation of Magnesium Extrusion Production

2005 ◽  
Vol 488-489 ◽  
pp. 483-486 ◽  
Author(s):  
Ming Zhou ◽  
Jianyong Cao ◽  
Fulin Yu ◽  
Xia Wei
Keyword(s):  
Magnesium Alloy ◽  
High Pressure Processing ◽  
Alloy Development ◽  
Molding Process ◽  
Specific Strength ◽  
Hexagonal Close Packed ◽  
Slip Planes ◽  
Copper Zinc ◽  
Increasing Temperature ◽  
Development Application

Compared with any other pressure processing methods, extrusion is more prone to develop the plasticity of the metal. Extrusions have much better size precision and surface quality than products by rolling and forging. As one-shot molding process, extrusion can eliminate some machining. In addition, extrusions have very high strengths and elongations because of their compact interior structures and fine grains. This paper summarizes some experiences and plans in extrusion production of CQMST(Chongqing Magnesium Science & Technology Co.Ltd). Magnesium, a plentiful element with density of 1.78g/cm3，2/3 of aluminum and 1/4 of steel, is characterized by its high specific strength and toughness, good dumping performance, thermal conductivity and electromagnetism shielding as well as recyclability. Following the advancing technologies of magnesium smelting, high pressure processing, surface treatment and soldering since 1990’s, the prices of magnesium and its ingot stepped down. As an important light engineering material, magnesium application is growing at annual speed of 15%, much higher than aluminum, copper, zinc, nickel and steel. In China, magnesium and magnesium alloy development, application and industrialization has been placed on the National “Tenth Five-year Plans” and the National “863” Scheme, which indicated the coming of new age for magnesium and magnesium alloy development and application in China. In the past, most of the magnesium products were produced by casting, especially die casting and thixomolding. It’s always considered that the crystal structure of magnesium is hexagonal close-packed, and only two slip planes exist at room temperature, so compared with other alloys, it’s very difficult to produce magnesium parts by forging, rolling or extrusion. Nevertheless, practice showed that if heated to a certain temperature, magnesium extrusion may not be hard work, and even easier than 5056 and 2024 aluminum. When extruded with distributary die, magnesium alloy can have better soldering performance than aluminum alloys mentioned above, just because new slip system forms along with increasing temperature (>225°C) and accordingly increases the plasticity of magnesium.

Effect of Temperature on the Dynamic Compressive Properties of Magnesium Alloy AZ91D

2013 ◽  
Vol 535-536 ◽  
pp. 133-136 ◽  
Author(s):  
Iram R. Ahmad ◽  
Xiao Jing ◽  
Dong W. Shu
Keyword(s):  
Magnesium Alloy ◽  
Strain Rate ◽  
Effect Of Temperature ◽  
Damping Capacity ◽  
Specific Strength ◽  
Alloy Az91d ◽  
Structural Applications ◽  
Protective Structures ◽  
Increasing Temperature ◽  
Stiffness And Damping

Lightweight materials are getting more and more attraction towards their use in automobiles, planes, protective structures, electronics and supports for numerous benefits ranging from reduction in fuel consumption in vehicles to lighter and stronger in protective structures. For efficient use of materials in applications where they are subjected to unusual higher sudden loads and varying temperatures, it is necessary to know their accurate response under such conditions. Magnesium alloys due to low density, high specific strength, high specific stiffness and damping capacity have been in use for variety of structural and non-structural applications mainly in automotive and aerospace industries along with many other applications in defense, supports and electronics. In present study, the effect of temperature variation has been investigated for magnesium alloy AZ91D at high strain rates. The temperature is varied in the range between -30oC to 200oC at a strain rate of 103 s-1. Lower stresses and larger strains to peak compressive stresses are observed with increasing temperature. At higher strain rate, the effect of temperature on the alloy’s hardening behaviour is less significant

scholarly journals Fracture of Be and Its Alloys - Webb Space Telescope Revisited

2021 ◽  
Author(s):  
Muhammad Musaddique Ali Rafique
Keyword(s):  
Near Infrared ◽  
Joint Venture ◽  
Coefficient Of Thermal Expansion ◽  
Infrared Range ◽  
Linear Coefficient ◽  
Space Telescope ◽  
Hexagonal Close Packed ◽  
James Webb Space Telescope ◽  
Layer Deposition ◽  
Slip Planes

NASA/ESA/CSA joint venture James Webb Space Telescope is about to be launched. It is hypothesized to operate in near-infrared range. It is also hypothesized to unveil early star formation, galaxies, and universe due to its orbit, point in orbit and orbital motion. It has been under manufacturing for over 20 years at a staggering cost of 10 billion US dollars (most expensive scientific experiment in history). Beryllium (Be) is chosen to be element for construction of its main mirrors due to its high stiffness, low density, low linear coefficient of thermal expansion (α) in cryogenics and high thermal conductivity. It is followed by gold (Au) layer deposition on its (Be) surface to enhance its sensitivity towards infrared radiation as later is hypothesized to bear superior properties. However, serious mistakes have been made in selecting this material for this application. Owing to its crystal structure (hexagonal close packed (hcp)), slip planes (basal, prismatic and pyramidal) and mechanisms of their activation, Be necessitates easy fracture at cryogenic temperature. It has anisotropic properties and prone to transverse fracture under tensile loading. Furthermore, its ductile to brittle transition temperature is very low making it entirely unsuitable for such an application. It is one of most expensive metals on planet. This study constitutes revisiting these fundamental properties and mechanisms which were entirely ignored during materials selection thus rendering whole project useless.

Microstructures and Mechanical Properties of AZ31+Sr+Y Magnesium Alloy Sheets Produced by Twin-Roll Casting and Sequential Hot Rolling

2013 ◽  
Vol 765-767 ◽  
pp. 3176-3179 ◽  
Author(s):  
Yan Dong Yu ◽  
Qiong Hu ◽  
Peng Jiang
Keyword(s):  
Magnesium Alloy ◽  
Hot Rolling ◽  
Room Temperature ◽  
Dominant Role ◽  
Boundary Slip ◽  
Twin Roll Casting ◽  
Roll Casting ◽  
Deformation Properties ◽  
Increasing Temperature ◽  
Twin Roll

In this paper, the deformation properties of AZ31+Sr+Y magnesium alloy sheets produced by twin-roll casting (TRC) and sequential hot rolling were studied by the tensile testing at a strain rate of 7×10-4s-1and various temperatures: room temperature (RT), 200°C, 300°C and 400°C, respectively. The result shows that the microstructure of AZ31+Sr+Y alloy was refined obviously by adding elements Sr and Y, the elongation of the alloy increased with increasing temperature, and the fracture behavior of the alloy changed from brittle fracture to ductile fracture with increasing temperature. During the process of plastic deformation of AZ31+Sr+Y alloy, the twin plays a leading role at room temperature; the dislocation movement is regarded as the main deformation mechanism at 200° C; at the higher temperature (above 300°C) the grain boundary slip (GBS) plays a dominant role .

Formability of AZ31 Magnesium Alloy Sheet in Dry Press Forming Using Diamond-Coated Dies

2009 ◽  
Author(s):  
S. Tsuda ◽  
S. Yoshihara ◽  
S. Kataoka
Keyword(s):  
Surface Roughness ◽  
Magnesium Alloy ◽  
Magnesium Alloys ◽  
Deep Drawing ◽  
Chemical Vapor ◽  
Alloy Sheet ◽  
Az31 Magnesium Alloy ◽  
Specific Strength ◽  
Press Forming ◽  
Forming Tools

Dry press forming which hasn’t used lubricants in the process is the attractive forming technique of zero emission for the lubricants. As one of the dry press forming techniques, the usage of dies coated with a chemical vapor deposition (CVD) diamond film, which are expected to be applied to forming tools owing to their high tribological properties, abrasion resistance and heat resistance, has been proposed. Magnesium alloys have attracted attention owing to their advantages over what such as, high specific strength and ease of recycling. However, they have intractable characteristics, and it is necessary to perform the forming technique at high temperature and to consider lubrication condition. In this study, diamond-coated dies were used in the deformation of magnesium alloy sheets without lubricants in press forming, and the formability of magnesium alloy and its effect on the surface texture of a formed-cup were investigated. Dry deep-drawing tests and dry ironing tests were carried out to estimate the effect of the diamond-coated dies on the formability of magnesium alloy sheets. Furthermore, the formability obtained using the above-mentioned tests was compared with that obtained in tests using non-lubricant dies with traditional lubricant. AZ31 magnesium alloy sheets (thickness: t0 = 0.5 mm) were deformed at 200 °C in dry deep-drawing tests. From the results, it was found that what can be deformed using diamond-coated dies. Moreover, a 20% reduction in drawing force was confirmed compared with the usage of the traditional lubricant (MoS2). Meanwhile, dry ironing tests were performed under conditions of 10% ironing ratio by a method similar to the dry deep-drawing tests. In general, the ironing process, which is the most difficult step in lubrication in sheet forming, has been enabled by the diamond coating technique. Furthermore, it was observed that the surface roughness of the formed-cup walls using the diamond-coated dies was 0.4 μmRz, and, 1.3 μmRz in case of MoS2. It was confirmed that the application of diamond-coated dies improved the surface roughness of the formed-cup. It produced an improvement in the formability of magnesium alloys compared with the traditional lubrication technique (use of MoS2). It was concluded that the validity of the use of diamond-coated dies became clear.

Damping Properties of AZ91D Magnesium Alloy with Y Addition

2012 ◽  
Vol 476-478 ◽  
pp. 3-10
Author(s):  
Hang Chen ◽  
Xuan Pu Dong ◽  
Xiao Qing Xiong ◽  
Rong Ma ◽  
Shu Qun Chen ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Magnesium Alloy ◽  
Fine Particles ◽  
Mechanical Analysis ◽  
Damping Capacity ◽  
Dislocation Model ◽  
X Ray Diffraction ◽  
Transmission Electron ◽  
Mg17al12 Phase ◽  
Increasing Temperature

The influence of Y on the microstructure and damping capacity of AZ91D based alloys was investigated by optical microscopy, X-ray diffraction, scanning electron microscopy, transmission electron microscopy and dynamic mechanical analysis. The results show that, with increasing Y content, the grain size of α-Mg matrix decreases tremendously and the distribution of β-Mg17Al12 phase is transformed from discontinuous network to fine particles. Meanwhile, a needle-shaped Al4MgY phase mainly distributing at the grain boundaries is identified. The damping capacity of the studied alloys shows sustained enhancement with increasing temperature. As to the strain dependent damping capacity, with the increase of Y content, the damping value of AZ91D alloy decreases gradually before Y content reaches to 0.5wt.%, and fluctuates when Y addition is between 0.5wt.%~0.9wt.%. G-L dislocation model was employed to explain the effects of parameters on damping capacity of magnesium alloy.

scholarly journals Achievements in Deep Drawing of Magnesium Alloy Sheets

2011 ◽  
Vol 690 ◽  
pp. 302-305 ◽  
Author(s):  
Lennart Stutz ◽  
Julian Quade ◽  
Michael Dahms ◽  
Dietmar Letzig ◽  
Karl Ulrich Kainer
Keyword(s):  
Magnesium Alloy ◽  
Deep Drawing ◽  
Elevated Temperatures ◽  
Hydraulic Press ◽  
Drawing Ratio ◽  
Transportation Industry ◽  
Specific Strength ◽  
Az31 Sheet ◽  
Dynamic Recrystallisation ◽  
Strength And Stiffness

Magnesium alloy sheets bear significant potential in replacing conventional materials such as aluminium and steels in ultra lightweight designs. High specific strength and stiffness, combined with the lowest density of all structural metals make magnesium alloy sheets candidates to face the challenges of reducing vessel weight in the transportation industry and thus, green house gas emissions. For forming components from sheet metal, deep drawing is a well established and commonly applied process. Due to the limited formability of magnesium sheets at room temperature, deep drawing processes have to be conducted at elevated temperatures. In the present study, hot deep drawing experiments on an industrial scale hydraulic press were successfully conducted. Forming was done at moderately low temperatures from 150°C to 250°C. Sheets of the magnesium alloy AZ31B (Mg-3Al-1Zn-Mn) were drawn to symmetrical cups according to Swift. For AZ31, distinct basal type textures are formed during hot rolling. The influence of texture on earing is displayed. The microstructural evolution of the material is dominated by the formation of twins and dynamic recrystallisation. By optimising the process, a drawing ratio of 2.9 was achieved for AZ31 sheet, outperforming conventional materials at ambient temperature.

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