Affect of magnesium as an alloying element in cold rolled 3003, 3005 and 3105 aluminium alloys

It is well known that aluminium is the third abundant metal on earthcrust after silicon and oxygen. Before chemists developed inexpensive ways to produce pure aluminum, it was considered a somewhat precious metal. In fact, in 1855, a bar of pure aluminum metal was displayed at the Paris Exposition. It was placed next to the French crown jewels! Aluminum production is a two-step process. First, aluminum oxide is separated from bauxite by the Bayer process. In this process, bauxite is mixed with sodium hydroxide (NaOH), which dissolves the aluminum oxide. The other compounds in bauxite are left behind. The aluminum oxide is then treated with a process similar to the Hall method. There is not enough natural cryolite to make all the aluminum needed, so synthetic (artificial) cryolite is manufactured for this purpose. The chemical reaction is the same with synthetic cryolite as with natural cryolite. About 21 million metric tons of aluminum were produced in 1996 by this two-stage process. It is widely used in automotive industry, packaging, heat exchangers and etc because of its lightness, corrosion resistivity and high strength. After 1960's it became the second most consumed metal after steel. Before this date it was the copper. Annually 30 million tones of aluminium are consumed and many of them can be recycled and used again. Commercially there are 8 series of aluminium alloy. Aluminium alloys are alloys in which aluminium (Al) is the predominant metal. The typical alloying elements are copper, magnesium, manganese, silicon, tin and zinc. There are two principal classifications, namely casting alloys and wrought alloys, both of which are further subdivided into the categories heat-treatable and non-heat-treatable. About 85% of aluminium is used for wrought products, for example rolled plate, foils and extrusions. Cast aluminium alloys yield cost-effective products due to the low melting point, although they generally have lower tensile strengths than wrought alloys. The most important cast aluminium alloy system is Al–Si, where the high levels of silicon (% 4.0–13) contribute to give good casting characteristics. Aluminium alloys are widely used in engineering structures and components where light weight or corrosion resistance is required. These series can show different and significant features when they are compared with each others. 1xxx series of aluminium are the purest series and it almost contains more than %99.5 aluminium. Is is widely used as a heat exchanger. Aluminium alloy surfaces will formulate a white, protective layer of corrosion aluminium oxide if left unprotected by anodizing and/or correct painting procedures. In a wet environment, galvanic corrosion can occur when an aluminium alloy is placed in electrical contact with other metals with more negative corrosion potentials than aluminium, and an electrolyte is present that allows ion exchange. Aluminum is used as pure metal, in alloys, and in a variety of compounds. An alloy is made by melting and then mixing two or more metals. The mixture has properties different from those of the individual metals. Aluminum alloys are classified in numbered series according to the other elements they contain. The 1000 classification is reserved for alloys of nearly pure aluminum metal. They tend to be less strong than other alloys of aluminum, however. These metals are used in the structural parts of buildings, as decorative trim, in chemical equipment, and as heat reflectors. The 2000 series are alloys of copper and aluminum. They are very strong, are corrosion (rust) resistant, and can be machined, or worked with, very easily. Some applications of 2000 series aluminum alloys are in truck paneling and structural parts of aircraft. The 3000 series is made up of alloys of aluminum and manganese. These alloys are not as strong as the 2000 series, but they also have good machinability. Alloys in this series are used for cooking utensils, storage tanks, aluminum furniture, highway signs, and roofing. Alloys in the 4000 series contain silicon. They have low melting points and are used to make solders and to add gray coloring to metal. Solders are low-melting alloys used to join two metals to each other. The 5000, 6000, and 7000 series include alloys consisting of magnesium, both magnesium and silicon, and zinc, respectively. These are used in ship and boat production, parts for cranes and gun mounts, bridges, structural parts in buildings, automobile parts, and aircraft components. The largest single use of aluminum is in the transportation industry (%28). Car and truck manufacturers like aluminum and aluminum alloys because they are very strong, yet lightweight. Companies are using more aluminum products in electric cars. These cars must be lightweight in order to conserve battery power. General Motors, Ford, and Chrysler have all announced advanced new car designs in which aluminum products will be used more extensively. Aluminum producers also plan to make a wider variety of wheels for both cars and trucks. Twenty-three percent of all aluminum produced finds its way into packaging. Aluminum foil, beer and soft drink cans, paint tubes, and containers for home products such as aerosol sprays are all made from aluminum. Fourteen percent of all aluminum goes into building and construction. Windows and door frames, screens, roofing, and siding, as well as the construction of mobile homes and structural parts of buildings rely on aluminum. The remaining %35 of aluminum goes into a staggering range of products, including electrical wires and appliances, automobile engines, heating and cooling systems, bridges, vacuum cleaners, kitchen utensils, garden furniture, heavy machinery, and specialized chemical equipment. Approximately 15 million tonnes of aluminium alloys use pure magnesium as an alloying element. 80% of the world's production of aluminium wrought alloys and 60% of the world's production of cast alloys use magnesium as an alloying addition. For the former category, additions of % 0.1 - % 4.4 magnesium improve the formability and weldability of aluminium alloys. For the latter category, additions of % 0.3 - % 1.5 magnesium improve the corrosion resistance and tensile properties of aluminium alloys following heat treatment. The magnesium containing aluminium alloys are used in 3 principal industries: Packaging accounts for % 50 of the demand for magnesium in the aluminium sector, consuming approximately 70,000 tonnes per annum. The principal use of magnesium containing alloys in this sector is for beverage cans. Other applications include aluminium foils, food cans and aerosol canisters. The automobile industry consumes % 35 or 50,000 tonnes of the magnesium being supplied to the aluminium industry. Wrought alloys containing magnesium are used primarily in the production of automotive sheet, while cast alloys containing magnesium are used in the production of cylinder heads, pistons and engine blocks. Structural extrusion profiles in the construction industry account for the remaining % 15 of the demand for magnesium in the aluminium alloying sector, totaling some 20,000 tonnes. Whenever aluminium products are fabricated by rolling, extruding, drawing, bending, etc., work is done on the metal. When work is done below the metal's recrystallisation temperature (cold work), it not only forms the metal, but also increases it strength due to the fact that dislocations trying to glide on different slip planes interact causing a "traffic jam" that prevents them from moving. Fabricating processes carried out above the metal's recrystallization temperature (hot work) do not normally increase strength over the annealed strength condition. With non heat-treatable wrought alloys, cold work is the only way of increasing strength. With heat treatable alloy, cold work applied after heat treating can increase strength still further. In this paper we are going to investigate the affect of magnesium in 3003, 3005 and 3105 aluminium alloys. Percentage of silicon and iron are almost same in these 3 metals; but when there is approximately %1.10 manganese in 3003 alloy, there is %1.20 magnesium in 3005 as an alloying element. 3105 contains nearly half of this amount of magnesium and manganese. After taking samples from twin roll casting stand, samples' size are 6 mm thickness, 2000 mm length and 100 mm width. Samples were cut into small sizes for annealing and cold rolling. First of all, samples were annealed at 580 0C for 8 hours and respectively they were annealed 550 0C for 8 hours and 520 0C for 8 hours. After annealing they were rolled to 2 mm and at this thickness they annealed again at 410 0C for 4 hours. Lastly they were rolled again to 0,50 mm and for the last time they were annealed at 350 0C for 4 hours. After the first annealing, it was taken hardness and strength values of the alloys. When we compared them, we saw that magnesium can effect both strength and hardness. 3005 alloy is harder and it has more strength than the other two alloys.