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ALLOY CHOICE
PROCESSES
POST FORMING |
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One of the advantages of the Superforming process is the range of aluminium alloys that can be formed providing solutions to virtually any engineering problem. The Superforming process was initially developed to take advantage of a property of certain aluminium alloys called superplasticity. What this means is that when the alloy is heated to about 500 degrees centigrade the material can be stretched without it breaking. This behaviour is only evident in certain alloys and the effect is shown below:
As can be seen above, the superplastic alloy will stretch and stretch without failure whereas the standard alloys will only go to a certain point before failure. This behaviour is different in different alloys. This ability to stretch is what allows the alloys to be formed into complex 3D shapes. Obviously, the degree of elongation that can be achieved dictates the complexity of the form for each alloy. Where one alloy may be formed easily another may not be possible. Different alloys have different mechanical and physical properties and this must be taken into consideration during the design process. It may well be possible to form a complex shape in one alloy but that alloy may not have the properties required for in service use. Primary structure applications for the Aerospace industry require high strength alloys accompanied with good service properties such as fatigue toughness and stress corrosion. These requirements are adequately met with the alloy 7475 which, for example, has been used successfully to form air intake lip skins and access door assemblies. For less demanding applications the heat treated version of 2004 has found many applications for secondary structures such as aerodynamic fairings and stiffeners. In the formed condition the alloy has suitable mechanical properties for internal fittings such as kicking panels and light fittings. The 2004 alloy exhibits excellent superplastic properties and is generally the most suitable for complex forms required by the electronics industry and has been used to manufacture equipment covers and cases for lap top computers. Outside the aerospace and electronics industries the alloy 5083 is widely used for both internal and external applications. This alloy has high corrosion resistance combined with excellent post forming and welding properties which makes it an ideal choice for transport and architectural applications. Many prestigious buildings and new trains now benefit from the use of this alloy and the forms that can be achieved by the SPF process. At Superform we have literally decades of experience in using aluminium alloys and we can advise on design and material suitability for a particular application. We produce a range of material data sheets and design guides available upon request - just fill in the request form here or email our sales team. |
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