Rolled aluminum - it's all long articles of deformed aluminum alloys. They are obtained by various methods of hot and cold plastic deformation - rolling, pressing (extrusion), drawing.
Alloys for rolled aluminum
The main groups of alloys for aluminum products, which are made by hot and cold deformation methods - mostly by rolling and pressing, which are most often used in practice, except for technically pure - unalloyed - aluminum, are aluminum alloys with:
- magnesium and manganese;
- magnesium and silicon;
- zinc and magnesium;
- copper and magnesium;
- zinc, magnesium and copper.
These aluminum alloys - deformable alloys - are used in various methods of metal forming - rolling., pressing and drawing, as well as stamping and forging. However, the overwhelming majority of products from these aluminum alloys are rolled aluminum - long semi-finished products and products:
- thick and thin sheets,
- pipes and so on.
Aluminum - and especially rolled aluminum - is used in all areas of industry. The need for lighter and stronger semi-finished products and products is a driving force for the continuous improvement of standard alloys in terms of their chemical composition., properties and manufacturing technologies. Competition with new non-metallic materials requires further development of new aluminum alloys.
High-strength aluminum alloys
The most high-strength aluminum alloys are alloys of the aluminum-copper-magnesium and aluminum-zinc-magnesium-copper systems. The strength of the latter reaches 600 MPa and higher with very high fracture toughness - 30 MPa m1/2. These alloys are widely used in transport engineering., including, in aircraft construction, due to high strength / weight ratio. These alloys are used mainly in the form of rolled aluminum - high-strength aluminum sheets.
Alloys of the aluminum-magnesium-silicon and aluminum-manganese systems are used for extruded aluminum rolled products - profiles, pipe, bars.
Rolled aluminum for aircraft
7xxx series aluminum alloys contain zinc as the main alloying element. They are known for their high strength, which makes them suitable for use, for example, in load-bearing elements of aircraft. These alloys provide a combination of increased strength and high toughness properties, as well as reduced sensitivity to hot cracking during welding. The hardness of these alloys in the aged state reaches 180 NV.
alloys 7075 and 7055 are good examples of alloys for aircraft aluminum rolling. They are widely used in the aerospace industry for their high strength..
Alloy 7055 It contains 7,6-8,4 % zinc; 1,8-2,3% magnesium; 2,0-2,6 % copper; 0,08-0,25 % zirconium with limited silicon and iron content.
Alloy 7075 It contains 5,1-6,1 % zinc; 2,1-2,9 % magnesium; 1,2-2,0 % copper, 0,18-0,28 % chromium with limited silicon content, iron and manganese.
Artificial aging of these alloys for maximum strength usually involves heating for 20 hours or more at temperatures from 100 to 150 degrees Celcius. This state of the material is designated as T6. In this state, However, alloy 7075 and similar alloys are prone to stress cracking, subsurface corrosion and intergranular corrosion.
Rolled aluminum for car bodies
low density, good workability, fairly high strength and good corrosion resistance of aluminum alloys meets the requirements for sheet metal, which is used in the manufacture aluminum body cars and other road vehicles. These properties also make it possible to meet increasingly stringent environmental requirements and, Moreover, provide easy and cheap post-life recycling of aluminum products.
Automotive sheet - steel and aluminum
Replacing steel sheets with aluminum ones means lowering the car body by 40-50 %. The lower stiffness of aluminum sheets is one of the few disadvantages compared to steel sheets.. This is compensated by the use of aluminum sheets on 50 % thicker, than steel sheets. This simultaneously increases the safety of the vehicle.. strength properties aluminum body sheets car slightly lower, than conventional deep heading steel sheets. Due to the higher thickness of the aluminum sheets, to achieve the rigidity they need, as well as increasing their strength due to artificial aging, the strength of the aluminum body is comparable to that, which have a steel body.
The production of aluminum sheets for car bodies is more expensive, than steel sheet production. This is due to the lower ability of aluminum to deep planting, more technological stages, as well as a more expensive instrument. In terms of weight loss, energy saving and subsequent recycling of scrap aluminum already has an advantage over steel.
Aluminum Alloys For Automotive Sheet
Various manufacturers have developed a range of alloys specifically for aluminum sheets, of which car bodies are made. They are based on standard aluminum alloys.
These alloys include alloys 5754, 5182, 6016, 6009, 6111 and 2036.
Alloy 5754 has a nominal magnesium content 3,1 %, a raft 5182 – 4,5 %. Alloy 6016 It contains 1,25 % silicon, and 0,40 % magnesium, a raft 6009 – 0,8 % silicon, 0,40 % copper, 0,50 % manganese and 0,60 % magnesium. In the alloy 6111 contains 0,9 % silicon, 0,70 % copper, 0,30 % manganese and 0,75 % magnesium. Alloy 2036 refers to the 2xxx series: 2,6 % copper, 0,25 % manganese and 0,45 % magnesium.
alloys 5754 and 5182 used in the annealed - softest - state, and heat-hardening alloys 6009, 6016, 6111 and 2036 - in state T4, which means naturally aged condition.
Alloys of the aluminum-magnesium series - 5xxx series - are not heat-strengthened. They belong to medium strength materials.. Their ability to plastic deformation and strength depends on the magnesium content - increasing the magnesium content increases the strength, and the plasticity decreases. Sheets in a soft state are easier to form by stretching and deep upsetting, than, let us say, sheets of alloys of the aluminum-magnesium-silicon system – 6xxx series. The most commonly used alloys are AlMg2.5, AlMg3 и AlMg5Mn. Some 5xxx series alloys also contain copper. Copper increases strength as a result of the aging process. In the same time, copper reduces the alloy's resistance to corrosion.
A source: www.totalmateria.com