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At the smallest level, chemical elements consist of atoms. The atoms of a given element all have the same structure but there are differences between the atoms of the different elements. Chemical compounds are formed between two or more elements when the atoms combine to form molecules.
The atomic nucleus is located at the centre of the atom and
It is important in industry that users and processors of aluminium also have a basic knowledge of its physical and chemical properties.
A basic understanding of the metal’s structure and its important properties is a prerequisite for using it in the best possible way. This also includes, of course, knowing the possible effects of the surrounding
This section covers several aspects. Click on one of the topics below to obtain further information about it:
General principle of forging
Forgings
Typical applications
Forging alloys
Microstructure / forged structure
Defects in the forged structure
Forging temperatures
Summary
With forging, one differentiates between open-die or hammer forging
Metal injection moulding (MIM), which is a form of powder injection moulding, is a new process that allows aluminium powder to be processed into complex components. As with injection moulding of plastics, the process is a large-scale production process that allows intricate components to be produced economically.
The first step in the metal
Electrolysis is generally used to describe the decomposition of an electrolyte by means of electrical current. The electrolyte is an electrically conducting fluid, such as a solution of salts. The molecules of the dissolved substance are broken down into ions, i.e. electrically charged atoms.
If one uses two electrodes immersed in the electrolyte
Aluminium foam is regarded as being a very porous metallic substance. In order to produce it, aluminium is foamed to obtain a specifically light material with a cellular structure. It is possible to create pores that are either open or closed.
Foamed aluminium is characterised by a high stiffness and low specific weight. In addition, it is a first
This section covers several aspects. Click on one of the topics below to obtain further information about it:
Refined aluminium
Crystal structure
Tabular overview of the most important properties
Properties and applications
Electrical conductivity
Thermal conductivity
Magnetic properties
Optical properties
Summary
On a microscopic scale,
The process of die-casting
With die-casting, the fused material is injected into the mould at high pressure and with high speed. Appropriate for die casting are primarily metallic materials with a low fusing point like aluminium alloys (in the first place Al-Si, Al-Si-Cu und Al-Mg) and zinc or magnesium.
The mould comprises two halves, with one
The electrical conductivity of aluminium with a 99.99% degree of purity is 63.8% of the International Annealed Copper Standard. On a weight-to-weight basis, however, the electrical conductivity of aluminium is about twice that of copper. For this reason, aluminium has been used exclusively in overhead power lines for a good many years.
Electrical
With aluminium alloys, the forming temperature is between 320 °C and 480 °C depending on the composition. The forging temperature range is, however, very narrow. With forging, the metalworking process itself results in heat being transferred to the metal. The temperature of the tool is thus determined on the basis of the (logarithm of the) degree
Permanent moulds, which are also called chills or chill moulds, are reusable moulds made from hot-working steel or cast iron with lamellar graphite. Depending on the mould material and the geometry of the part, they have a relatively high service life (shape stability). Cavities and undercuts are created using metal cores (so-called slides). Cores
Aluminium and aluminium alloys are very weakly paramagnetic, i.e. they are only very weakly attracted by a magnet. Alloying elements only have a negligible effect so that aluminium alloys can be regarded as being practically non-magnetic. Use is made of this property, for example, to shield sensitive electronic equipment.
Investment casting is often referred to as the lost-wax process. This method of casting is also based on the “expendable mould” principle. The patterns are made of wax or a special plastic using injection moulding in metal moulds. The patterns are then nested together like a bunch of grapes. They are dipped repeatedly in a ceramic slurry until
During extrusion the metal is forced at high pressure through a tool, the so-called die, whose shape determines the form of the profile.
The tooling is held in place during extrusion by a locking device that prevents it from moving. Dies thus have to be capable of withstanding high stresses and temperatures of around 250-350 °C. They are usually
Aluminium powder, which is silvery white in appearance, is the finest form of aluminium. Because of its fineness there is a potential risk of explosion or fire when it comes into contact with oxidising agents. Spontaneous combustion is possible on contact with air. Aluminium powder produces hydrogen when it combines with water, acids or alkalis.
In addition to the wide range of methods of surface finishing available, one can also influence the surface condition of the product during the rolling process. The characteristics of the rolled surfaces or the surface finish of the rolls are transmitted to the strip surface. This standard surface finish is also called a ‘mill finish’. Special