aluminium technologies 24.11.2015
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Comparison of casting processes Elongation levels of conventional pressure die castings are limited. Hence, pressure die cast components are not suitable for safety critical parts. High strength together with elongations much higher than %10 have been obtained with casting methods that use even higher pressures, such as squezze and semi-solid casting. Hence, they are referred to as «high integrity casting methods».
Primary and secondary alloys Primary alloys are produced by adding alloying elements to pure aluminium. Secondary alloys, on the other hand, are produced from recycled metal at much lower costs. Recycled material is almost always contaminated with iron. Secondary alloys thus contain high levels of Fe and other impurities. Fe has a negative effect on castability and ductility and other properties. The Fe content must be controlled to a minimum for these reasons.
Primary and secondary alloys The only exception to a low-fe level is pressure die casting alloys. In sand and permanent mold casting, for applications that require high ductility, Fe must be controlled below < 0.20 %. This actually means primary alloy. Fe may be higher when ductility is not critical. When castability and machinability are important Fe can be as high as %0.5 and even higher. Secondary aluminium alloys can be used in such cases.
casting alloy designations Aluminum casting alloys are numbered in accordance with a 3 digit-plus-decimal designation in order to identify major alloying elements (and some alloy combinations). The digit following the decimal in each alloy number indicates the form of product. 0 : the chemistry limits applied to an alloy casting. 1 : the chemistry limits for ingot used to make the alloy casting. 2 : the chemistry limits for ingot are different (typically tighter).
casting alloy designations Generally, the XXX.1 designation indicates the ingot is supplied as a secondary product (e.g., remelted from scrap), whereas the XXX.2 designation suggests the ingot is produced from primary aluminum. Some alloy names are preceded by a letter so as to distinguish between alloys that differ only slightly in percentages of impurities or minor alloying elements (e.g., 356.0, A356.0, B356.0 or F356.0).
Sand casting alloys Si Fe Cu Mn Mg Cr Ni Zn Sn Ti 201.0 0.10 0.15 4.0 5.2 0.20 0.50 0.15 0.55............ 0.15 0.35 204.0 0.20 0.35 4.2 5.0 0.10 0.15 0.35... 0.05 0.10 0.05 0.15 0.30 242.0 0.7 1.0 3.7 4.5 0.35 1.2 1.8 0.25 1.7 2.3 0.35... 0.25 295.0 0.7 1.5 1.0 4.0 5.0 0.35 0.03...... 0.35... 0.25 319.0 5.5 6.5 1.0 3.0 4.0 0.50 0.10... 0.35 1.0... 0.25 328.0 7.5 8.5 1.0 1.0 2.0 0.20 0.6 0.20 0.6 0.35 0.25 1.5... 0.25 355.0 4.5 5.5 0.6 B 1.0 1.5 0.50 B 0.40 0.6 0.25... 0.35... 0.25 356.0 6.5 7.5 0.6 B 0.25 0.35 B 0.20 0.45...... 0.35... 0.25 443.0 4.5 6.0 0.8 0.6 0.50 0.05 0.25... 0.50... 0.25 512.0 1.4 2.2 0.6 0.35 0.8 3.5 4.5 0.25... 0.35... 0.25 514.0 0.35 0.50 0.15 0.35 3.5 4.5...... 0.15... 0.25 520.0 0.25 0.30 0.25 0.15 9.5 10.6...... 0.15... 0.25 535.0 0.15 0.15 0.05 0.10 0.25 6.2 7.5............ 0.10 0.25
Sand casting alloys Si Fe Cu Mn Mg Cr Ni Zn Sn Ti 705.0 707.0 0.20 0.8 0.20 0.40 0.6 1.4 1.8 0.20 0.40 0.20 0.8 0.20 0.40 0.6 1.8 2.4 0.20 0.40... 2.7 3.3... 0.25... 4.0 4.5... 0.25 710.0 0.15 0.50 0.35 0.65 0.05 0.6 0.8...... 6.0 7.0... 0.25 712.0 0.30 0.50 0.25 0.10 0.50 0.65 0.40 0.6... 5.0 6.5... 0.15 0.25 713.0 0.25 1.1 0.40 1.0 0.6 0.20 0.50 0.35 0.15 7.0 8.0... 0.25 771.0 0.15 0.15 0.10 0.10 0.8 1.0 0.06 0.2... 6.5 7.5... 0.10 0.20 850.0 0.7 0.7 0.7 1.3 0.10 0.10... 0.7 1.3... 5.5 7.0 0.20 851.0 2.0 3.0 0.7 0.7 1.3 0.10 0.10... 0.30 0.7... 5.5 7.0 0.20 852.0 0.40 0.7 1.7 2.3 0.10 0.6 0.9... 0.9 1.5... 5.5 7.0 0.20
Permanent mold casting alloys Si Fe Cu Mn Mg Cr Ni Zn Sn Ti 204.0 0.20 0.35 4.2 5.0 0.10 0.15 0.35... 0.05 0.10 0.05 0.15 0.30 208.0 2.5-3.5 1.2 3.5-4.5 0.50 0.10 0.35 1.0 0.25 222.0 2.0 1.5 9.2-10.7 0.50 0.15-0.35 0.50 0.8 0.25 242.0 0.7 1.0 3.7 4.5 0.35 1.2 1.8 0.25 1.7 2.3 0.35... 0.25 296.0 2.0 3.0 1.2 4.0 5.0 0.35 0.05... 0.35 0.50... 0.25 308.0 5.0-6.0 1.0 4.0-5.0 0.50 0.10 1.0 0.25 319.0 5.5 6.5 1.0 3.0 4.0 0.50 0.10... 0.35 1.0... 0.25 332.0 8.5 10.5 1.2 2.0 4.0 0.50 0.50 1.5 0.50 1.0... 0.25 333.0 8.0-10.0 1.0 3.0-4.0 0.50 0.05-0.50 0.50 1.0 0.25 336.0 11.0-13.0 1.2 0.50-1.5 0.35 0.7-1.3 2.0-3.0 0.35 0.25 354.0 8.6-9.4 0.20 1.6-2.0 0.10 0.4-0.6 0.10 0.20 355.0 4.5 5.5 0.6 B 1.0 1.5 0.50 B 0.40 0.6 0.25... 0.35... 0.25 356.0 6.5 7.5 0.6 B 0.25 0.35 B 0.20 0.45...... 0.35... 0.25
Permanent mold casting alloys Si Fe Cu Mn Mg Cr Ni Zn Sn Ti 357.0 6.5-7.5 0.15 0.05 0.03 0.45-0.6 0.05 0.20 359.0 8.5-9.5 0.20 0.20 0.10 0.50-0.70 0.10 0.20 443.0 4.5 6.0 0.8 0.6 0.50 0.05 0.25... 0.50... 0.25 513.0 0.30 0.40 0.10 0.30 3.5 4.5... 0.35... 0.25 535.0 0.15 0.15 0.05 0.1 0.25 6.2 7.5............ 0.10 0.25 705.0 0.20 0.80 0.20 0.4-0.6 1.4-1.8 0.2-0.4 2.7-3.3 0.25 707.0 0.20 0.80 0.20 0.4-0.6 1.8-2.4 0.2-0.4 4.0-4.5 0.25 711.0 0.30 0.7-1.4 0.35-0.65 0.05 0.25-0.45 6.0-7.0 0.20 713.0 0.25 1.1 0.4-1.0 0.6 0.2-0.5 0.35 0.15 7.0-8.0 0.25 850.0 0.7 0.7 0.7-1.3 0.10 0.10 0.7-1.3 5.5 7.0 0.20 851.0 2.0-3.0 0.7 0.7-1.3 0.10 0.10 0.3-0.7 5.5 7.0 0.20 852.0 0.40 0.70 1.7-2.3 0.10 0.6-0.9 0.9-1.5 5.5 7.0 0.20
Pressure die casting alloys Fe is an intended impurity as it avoids die soldering. Hence, the Fe content in this alloy group is identified with a minimum limit. Generally this limit is minimum %0.6 Fe. Secondary alloys are appropriate for die casting for this reason. The upper limit for Fe is determined by the level of ducitility required for that particular application. The upper limit is often between %1 and %1.3.
Pressure die casting alloys Pressure die castings are not heat treated because of the hydrogen gas problem. Hydrogen gas whether in solution or trapped in the casting having failed to escape during solidification, lead to blistering problems during solution heat treatments. General purpose die casting alloys: A380 (AlSi8Cu3) Rp=160 MPa, Rm =325 MPa, A5=0.5-3% A 383 (AlSi10Cu) Rp=150 MPa, Rm =310 MPa, A5=1-3%
Pressure die casting alloys Special pressure die casting alloys A443 (AlSi5) Rp0.2%=110 MPa, Rm =230 MPa, A5=9% When high ductility in addition to moderate strength is required; corrosion resistance is also high owing to low Cu content! A413 (AlSi12) Rp=140 MPa, Rm =300 MPa, A5=0.5-2% complex thin section components! A390 (AlSi17Cu4Mg) Rp=240 MPa, Rm=280 MPa, A5=1% a hypereutectic wear resistant alloy; used for engine blocks, compressor parts, brakes.
Pressure die casting alloys Si Fe Cu Mn Mg Ni Zn Sn Ti 360 9.0-10.0 2.0 0.6 0.35 0.4-0.6 0.50 0.50 0.15 - A360 9.0-10.0 1.3 0.6 0.35 0.4-0.6 0.50 0.50 0.15-380 7.5-9.5 2.0 3.0-4.0 0.50 0.10 0.50 3.0 0.35 - A380 7.5-9.5 1.3 3.0-4.0 0.50 0.10 0.50 3.0 0.35-383 9.5-11.5 1.3 2.0-3.0 0.50 0.10 0.30 3.0 0.15-384 10.5-12.0 1.3 3.0-4.5 0.50 0.10 0.50 3.0 0.35-390 16.0-18.0 1.3 4.0-5.0 0.50 0.45-0.65 0.10 1.5-0.10 413.0 11.0-13.0 2.0 1.0 0.35 0.10 0.50 0.50 0.15 - A413.0 11.0-13.0 1.3 1.0 0.35 0.10 0.50 0.50 0.15-443.0 4.5-6.0 2.0 0.6 0.35 0.10 0.50 0.50 0.15 -
Heat tretable Non heat tretable Aluminium foundry alloys alloy major element Solid solution strengthening 1xx >99 Al 4xx Si 5xx Mg Precipitation strengthening 2xx Cu 3xx Si + Mg (Cu) 7xx Zn 8xx Sn
Foundry alloy-summary Al-Cu alloys (2xx.x series) Heat treatable High-very high strength Low ductility Low corrosion resistance (sensitive to stress corrosion) Limited fluidity Hot tearing susceptibility applications Cylinder heads for car and aerospace engines, pistons for diesel engines, exhaust components
Foundry alloy-summary Al-Si-Cu-Mg alloys (3xx.x series) Heat treatable High strength Low ductility Good wear resistance Limited corrosion resistance (Cu bearing alloys) Good fluidity and castability Good machinability (Cu bearing alloys) applications Cylinder block and cylinder heads, wheels, airplane parts, compressor and pump components
Foundry alloy-summary Al-Si alloys (4xx.x series) Non heat treatable Medium strength Moderate ductility Good wear resistance Very good castability Good corrosion resistance applications Pump cases Thin section castings Cooking utensils
Foundry alloy-summary Al-Mg alloys (5xx.x series) Non heat tretable High corrosion resistance Good machinability High quality surface Perfect surface finish as anodised Adequate castability applications Various sand castings
Foundry alloy-summary Al-Zn alloys (7xx.x series) Heat tretable High dimensional stability Good corrosion resistance Poor castability Good machinability (Cu bearing alloys) applications High strength applications: both civil and military aerospace castings
Foundry alloy-summary Al-Sn alloys (8xx.x series) Limited strength Perfect wear resistance Good machinability applications Single and bi-metal bearing applications
casting alloy selection 242.0 A242.0 319.0 A319.0 B319.0 320 Cylinder heads, generator housings (aircraft), pistons (aircraft, diesel, motorcycle) Sand castings: crankcases (internal combustion and diesel Engines), pans (oil), tanks (gasoline and oil) Permanent mold castings: engine components (various), heads (watercooled cylinder), housings (rear axle) Applications where strength and hardness at high temperatures are desirable. Applications where moderate strength is required. Mechanical properties are not adversely affected by slight changes in impurity content.
casting alloy selection 356.0 Sand castings: brackets, blocks (water-cooled cylinder), automotive transmission cases, fittings, housings (rear axle), pump bodies Permanent mold castings: bodies (valve), blocks (engine), brackets (springs), elbows (fuel tanks), fittings (fuselage, tank car), hardware (marine), machine tool parts, pump parts, rudder-control supports A356.0 Airframes, chassis parts (trucks), machine parts, missile components, structural parts Applications where excellent casting characteristics are required. In the T6 condition for marine applications where pressure tightness and/or corrosion resistance are required. Applications where higher strength and higher ductility (especially elongation) are desirable.
casting alloy selection alloy Typical applications remarks A380.0 / B380.0 A390.0 / B390.0 Housings (lawn mowers), heads (air-cooled cylinders), gear cases, radio transmitters Blocks (internal-combustion engines), brakes, cylinder bodies (compressors), pistons (internal-combustion engines), pumps 535.0 Brackets, c-clamps, computing devices, instruments, machined parts 712.0 Castings (marine), farm machinery, machinetool parts Applications for generalpurpose die castings with good mechanical properties. Applications where high hardness, good wear resistance and low coefficient of thermal expansion are required. Applications requiring strength, shock resistance, ductility and dimensional stability. Applications requiring good strength, shock and corrosion resistance, machinability and dimensional stability
Heat treatment of castings Many castings are used in the as-cast condition, but certain applications require higher mechanical properties than the as-cast material. The proof stress of castings of alloy Al Si7 Mg for example, can be more than doubled by full heat treatment. For sand, gravity and low pressure die castings, all treatments are possible, though not all are standardised. Pressure die castings are not solution treated.
Heat treatment of castings Pressure die castings made using special processes such as vacuum die casting or squeeze casting contain less gas and may be solution treated. All die castings may be quenched from the die, precipitation treated and stress relieved without suffering harmful effects. Some heat treatments are carried out close to the melting point of the castings so accurate temperature control is needed. Forced air circulation furnaces are used to ensure that the temperature of all parts of the furnace is constant.
Heat treatment of castings the heat treatment of cast aluminium alloys is carried out to increase their strength and hardness and to change their physical, mechanical and metallurgical properties. Different types of castings require different thermal treatments. For example, improved mechanical and physical properties can be produced in sand and permanent-mold castings by heat treatment.
Heat treatment of castings By contrast, some alloys such as 443.0 that contain little or no copper, zinc or magnesium do not respond to heat treatment and do not exhibit improvements in mechanical properties. Others, such as die castings, can only be given a stress relief (and not solution heat treated) because of their porous internal structure due to fears of surface blistering and internal porosity.
Heat treatments for aluminium castings designation Heat treatment M TB (T4) TE (T5) TB7 TF (T6) TF 7 TS None; as-cast or as-manufactured Solution treated and naturally aged Artificially aged Solution treated and stabilized Solution treated and fully artificially aged Solution treated and artificially aged and stabilized Stress relieved and annealed
Solution Treatment TB (T4) Castings are heated to a temperature just below the alloy melting point (dependent on chemical composition) and held at this temperature (dependent on alloy and cross-sectional thickness) a sufficient amount of time to allow the alloying elements to enter into solid solution. Upon quenching, these elements are in a supersaturated metastable state. Quench media include water, boiling water or polymer.
Solution Treatment TB (T4) Choice of the quenchant is often a balance between achieving mechanical properties and managing distortion while avoiding the buildup of internal stresses in the part. Although mechanical properties increase somewhat by natural aging, precipitation hardening (artificially aging) is typically employed to achieve maximum benefit to the mechanical properties
Precipitation (Aging) TE Condition (T5 or T51) Artificial aging treatment is carried out at temperatures above ambient, typically in the range of 150-200 C, at relatively low temperatures to eliminate growth. Strength and hardness are increased. With chill castings (made in dies), it is possible to obtain some increase in strength of as cast components by precipitation treatment since the rapid cooling in the die retains some of the alloying constituents in solution.
Precipitation (Aging) TE Condition (T5 or T51) too long a time at temperature will result in a reduction in the mechanical properties. T5/T51 are also used to stabilize the castings dimensionally (improving mechanical properties somewhat) and to improve machinability. Soak (hold) times can vary between 2-24 hours depending upon the alloy and the cross-sectional thickness of the part. Lower temperatures and longer times promote precipitation and often enhanced mechanical properties.
Solution Treated and Stabilized TB7 After solution treatment, castings can be heated into the range of 200-250 C for stabilization and homogenization of the alloying elements. Times and temperature vary with the type of alloy and mass of the component.
Solution Treatment and Precipitation Hardening TF(T6 or T61) Solution treatment followed by precipitation (age) hardening produces the highest strength and mechanical properties (tensile and yield strength) while retaining ductility (elongation). Precipitation (age) hardening stabilizes the properties. Solution treated, quenched, precipitation treated and stabilised (TF condition) Castings used at elevated temperature, such as pistons, benefit from stabilisation treatment at 200 250 C following precipitation treatment. Some reduction in mechanical properties occurs.
Solution Treated and Stabilized TF7 Condition (T7 or T71) Castings used for elevated-temperature service may benefit from a solution treatment and stabilization between 200-250 C in order to stabilize mechanical properties when the component is exposed to temperatures close to or in this range. This heat treatment improves mechanical properties to a large degree, stabilizes the castings and usually results in a slightly lower tensile and yield strength but an increased elongation value compared to the T6 series of heat treatments.
Stress Relief and Annealing-TS Castings with varying section or having complex shape are likely to develop internal stresses in the mould or die because of differential cooling. The internal stresses may be released when the casting is machined, causing dimensional changes. Stress relief and annealing can be used to remove stresses in a casting or to soften the component for subsequent shaping or mechanical-working operations. Stress relief is typically performed between 200-250 C for 5 hours followed by slow cooling in the furnace. while annealing is done around 300-400 C.
wrought aluminium alloys
Wrought alloys Wrought alloys these alloys are hot and/or cold rolled, extruded, forged to final shape following either DC casting of ingots and billets or continuous casting of coiled strip! Strip, sheet and foil via hot and/or cold rolling Profile, tube, rod via extrusion Forming into various shapes Components with superior mechanical properties via forging.
Secondary alloying elements, impurities
Effect of alloying elements Iron The most common alloying element. Almost always present in aluminium alloys. Its solubility in liquid aluminium is high. Dissolves in the aluminium melt readily and its concentration increases rapidly. Its solubility in solid aluminium is very low and immediately forms coarse intermetallics upon solidification. Its compounds help to refine the grain size during rolling and subsequent interanneals.
Effect of alloying elements Manganese Improves strength both in solid solution and as intermetallic dispersoids. Helps to control the grain size. Promotes fibering during forming. Its dispersoids resists recovery and grain growth. Increases recrystallization temperature. Increases quench sensitivity. Used to modify the morphology of Fe-based intermetallics and compensate for their embrittling effect.
Effect of alloying elements Silicon Most common element in aluminium alloys after Fe. Calcium (Ca) Increases hydrogen solubility in liquid aluminium up to 10 ppm. Promotes hot tearing. Increases conductivity and affects recrystallization behaviour. Scandium (Sc) helps to control grain size. Used in high performance aluminium alloys such as bicycle profiles.
Effect of alloying elements Titanium Present in commercial aluminium alloys as much as 10-100 ppm. Decreases electrical conductivity. This is counteracted by the so called Boron treatment. Used as a grain refiner ve helps to limit cracking during solidification. These favourable effects become pronounced when added together with Boron.
Effect of alloying elements Boron Helps to control grain size at addition rates of 0.005-0.1 % More effective when used with Ti. Commercial grain refiners offer a Ti:B ratio of 5:1. Forms stable borides with transition elements such as V, Ti, Cr, Mo. The borides are removed from the melt through settlement leading to high conductivity: Boron treatment This is the most critical treatment in the manufacture of high conductivity aluminium alloys 1XXX and 6101!
Effect of alloying elements Chromium Helps to refine the grain structure! Gives yellow colour after anodization. Reduces conductivity İncreases toughness İncreases strength İmproves resistance to intergranular and stress corrosion. Vanadium Offers grain refinement. Reduces electrical conductivity. İncreases recrystallization temperature.
Effect of alloying elements Zirconium used up to 0.1-0.3 % in 7XXX alloys Forms very fine dispersoids and help to control grain structure through its effect on recovery and recrystallization reactions. tin Leads to surface blackening after annealing treatments when present up to 0.01%. Has a negative effect on susceptibility to corrosion when it segregates to the surface.
Effect of alloying elements Antimon Added to Al-Mg alloys at trace levels (0.01 01 ppm. İmproves corrosion resistance in salt water by forming a protective Sb-oxi chloride film on the surface. Some bearing alloys contain as much as 4 6% Sb. Sb can be used to replace Bi to avoid hot tearing in Al-Mg alloys.
Effect of alloying elements Berillium Harmful in packaging foil in contact with food and beverages as it leads to poisoning and must definitely be avoided. Bismuth (Bi) Used in Al-Mg alloys as much as 20 200 ppm to avoid hot tearing caused by Na.
Classification of wrought alloys The first digit indicates the alloy series The second digit indicates alloy modifications of an already existing alloy. For 1xxx series, the 3rd and 4th digits indicate the 0.XX % of aluminium higher than 99.00%. e.g. Al99.80 AA 1080 For the other series (2xxx to 8xxx) the 3rd and 4th digits identify a specific alloy without physical significance. They only serve to differentiate between various alloys. Note that the 8xxx series is not included in the diagram; this series contains all alloys with formulations that are special and fall out of the more standard formulations of the 1xxx to 7xxx series. A suffix "A" indicates a national variation of the alloy, e.g. EN AW-6005A.
Classification of wrought aluminium alloys 1XXX: AlFeSi 3XXX: AlMn 4XXX: AlSi 5XXX: AlMg Non heat treatable 8XXX: special 6XXX: AlMgSi 2XXX: AlCu 2XXX: AlCuMg 7XXX: AlZnMg heat treatable 7XXX: AlZnMgCu
1XXX series technically pure with at least 99 % Al very low strength main impurity elements are Fe and Si Fe and Si increase the strength of the alloy Iron results in a slight increase of strength and better creep characteristics at moderately elevated temperatures, for example for electrical conductors Iron also reduces the grain size
1XXX series fewer solute or precipitated alloy element species = fewer barriers against dislocation mobility, allowing easier plastic deformation. This leads to very high formability and workability. Superior corrosion resistance. Microstructure is largely free of intermetallics, the protective native oxide film is less disrupted and there are many fewer preferred anodic/cathodic reaction sites where corrosion can occur.this also makes these alloys very good for anodising. Highly reflective and decorative.
1XXX series Very high thermal and electrical conductivities the electrical and thermal conductivities fall as the solute content rises very suitable for packaging electronic devices, heating equipment (inertness and high conductivity for heat exchanger strip, radiator tubes, etc), lighting applications (high reflectivity for reflector casings, laser mirrors, etc) and decoration (high reflectivity and design appearance for furniture fittings, etc), amongst others.
2XXX serisi material strengthening by precipitation hardening, resulting in very strong alloys. Cu main alloying element (3 6 wt%), with or without Mg as alloying consituent (range 0 2 %) Cu also improves the fatigue properties, the high-t properties and the machinability of the alloy. Cu is however bad for the corrosion resistance.
2XXX serisi Cu tends to precipitate at grain boundaries, making the metal very susceptible to pitting, intergranular corrosion and stress corrosion. Cu is also very bad for anodising. The 2xxx series alloys are used for high strength structural applications such as aircraft fittings and wheels, military vehicles and bridges, forgings for trucks, etc. The low melting phase elements, lead and/or bismuth, facilitate machining of the 2xxx series alloys, making them also suitable for applications where hard extruded and machined parts are required (screws, bolts, fittings, machinery components, etc).
3XXX serisi Manganese as main alloying element in the 3xxx series (range 1 2 wt%) makes the alloys ductile, resulting in good formability while still allowing a wide range of mechanical properties through various strain hardened tempers. The 3xxx series are medium strength alloys.
3XXX serisi a very typical application is the beverage can body due to the alloys' good formability by pressing, roll forming and drawing. Also in other packaging, building (esp. architectural sheet), and home appliances applications these alloys are frequently used for their good combination of strength and formability, weldability, anodising behaviour (for building applications) and corrosion performance. Also for heating equipment, such as brazing sheet and heating tubes, 3xxx series alloys perform well with their relatively high thermal conductivity combined with medium strength and good corrosion resistance.
3XXX serisi Mn fine precipitates (dispersoids) also stabilise grain size during high temperature annealing which improves strength and formability. Manganese makes the alloy ductile; in combination with iron it improves the castability of the alloy and reduces shrinkage during metal solidification. In some of the 3xxx alloys, the strengthening effect of added Mn is supplemented by additions of magnesium which offers further solid solution strengthening (for example EN AW 3004 and EN AW 3104). Iron is a minor alloying element giving a polishing effect in fast deep drawing/ironing operations.
4xxx serisi 4xxx series have high silicon (up to 12 wt%) silicon is present in the form of intermetallic precipitates, but also as elemental silicon particles making the material brittle. They have very low formability. They find only a limited number of applications as wrought product, for example, as cladding alloy on brazing sheet because of its lower melting point than the core alloys of the 3xxx or 6xxx series or as filler metal for welding.
4xxx serisi Mostly the high silicon containing alloys are used for casting products where high rigidity/low ductility is required. Aluminium-silicon alloys containing high levels of Si are widely used in the foundry industry due to their high fluidity during casting and also because silicon reduces the shrinkage during freezing and the coefficient of thermal expansion of the cast product. High levels of Si make the alloy low ductile.
5xxx serisi The presence of magnesium as main alloying element in the 5xxx series (used up to 6 wt%) leads to solute hardening of the alloy, and efficient strain hardening, resulting in medium strenght. These alloys are generally stronger than the medium strength 3xxx series alloys, while having also very good formability. Except for susceptibility to intergranular corrosion under very unfavourable conditions (when the Mg level is > 3 wt%), the 5xxx series alloys have good corrosion performance, and especially their resistance in seawater and marine atm is superior to the other alloy series.
5xxx series The good formability, combined with the medium strength and excellent corrosion resistance, and the high quality anodising ability and weldability, result in many applications for outdoor exposure: in building architecture sheet (anodised and electrocoloured facade panels, for example), scaffolding, and especially marine applications (ship building, platforms, etc). Also in automotive, 5xxx series alloys are used for press formed body-parts and chassis components due to their good combination of strength and formability. Magnesium results in solute hardening of the alloy and thus increases the strength. Alloys in the 5xxx series may contain from about 0.8 wt% Mg to more than 5 wt% in the most highly alloyed variants.
6xxx series 6xxx series are high strength alloys that can be strenghtened by heat treatment (precipitation hardening), through the presence of their main alloying elements Si and Mg. These alloys are generally less strong than the 2xxx and 7xxx series, but have good formability and are weldable. They also have excellent corrosion resistance. The very good combination of high strength, formability, corrosion resistance and weldability results in a vast variety of applications for these alloys: transport (automotive outer body-panels, railcars, etc), building (doors, windows, ladders, etc), marine (offshore structures, etc), heating (brazing sheet, etc)
6xxx series Extruded 6xxx series alloys are also often used for machined products; by adding low melting phase elements such as lead, bismuth and/or tin 6xxx series alloys show very good machinability. These alloys can be easily anodised (often hard anodising for extruded parts of brake systems, electronic valves, pistons, etc) where hard surfaces, good corrosion resistance and high strength are required. For up to 12 % silicon, precipitation hardening of the alloys is possible when silicon is combined with magnesium making the 6xxx series strong alloys.
6xxx series Magnesium and silicon form Mg 2 Si precipitates. Furthermore, Si improves the corrosion resistance compared to other alloys except for those of the 1xxx series. Si also improves the fluidity of the molten alloy and reduces the susceptibility to hot crevicing during solidification and heating. More than 13 % Si reduces the machinability.
7xxx series 7xxx series are very strong "heat treatable" alloys; they can be strengthened through heat treatment (precipitation hardening) based on the combination of zinc (mostly 4 6 wt %) and magnesium (1 3 wt %). Unfortunately these alloys are prone to stress corrosion. Important critical applications of these alloys are based on their superior strength, for example in aerospace, space exploration, military and nuclear applications. But also structural parts in building applications can be from the 7xxx series, as well as high strength sports' attributes such as ski poles and tennis rackets.
7xxx series 7xxx series also have additions of magnesium to maximise their age-hardening potential where the precipitating phases are typically of the type MgZn 2. Such alloys give medium strength, but are relatively easily welded. Aluminium-zinc-magnesium alloys have a greater response to heat treatment than the binary aluminium-zinc alloys resulting in higher possible strengths. The additions of zinc and magnesium however decrease the corrosion resistance. Chromium amounts generally less than 0.35 % are added to increase the electrical resistivity.
7xxx series Cr also controls grain structure, by preventing recrystallisation in Al-Mg-Si and Al-Zn alloys during hot working or heat treatment. The fibrous structures thus retained reduce stress corrosion susceptibility and improve toughness. Cr in solid solution or finely dispersed increases strength slightly. The disadvantage of Cr in heat-treatable alloys (6xxx and 7xxx) is the increase in quench sensitivity when the hardening phase tends to precipitate on pre-existing Cr-based particles. Cr also tends to colour an anodic film yellow.
Common Minors, Traces & Unwanted Elements
Applications of wrought alloys
Applications of wrought alloys Aluminium foil: 1050 and other 1XXX alloys: high deformability and excellent corrosion resistance
Applications of wrought alloys 1350 alloy: overhead cables-conductors High electrical conductivity and adequate strength; corrosion resistance
Applications of wrought alloys 2024 / 7475 / 6013 alloys: Fuselage applications owing to high fatigue resistance and fracture toughness 7150 / 7449 / 7475 alloys: High fatigue resistance, fracture toughness, compressive strength and stiffness özellikleri ile alt underwing components 2024 alloy: high tensile strength, fatigue resistance and fracture toughness upper wing parts
Applications of wrought alloys 3104 alloy: Beverage cans 5182 alloy; Lid stock.
Applications of wrought alloys Heat exchangers 1050, 3003, 5059, 6101 alloys Good heat conductivity and in the case of 3XXX, 5XXX and 6XXX alloys, high strength Door, window and window blind profiles and panels 3XXX, 5XXX and 6XXX alloys high corrosion resistance, weldability and formability
Applications of wrought alloys Ship hull structures 5XXX and 6XXX alloys Good mechanical properties and corrosion resistance 5XXX alloys in sea water atmospheres
Applications of wrought alloys Car body panels 5754, 5182, 6016 alloys High strength, corrosion resistance 5754 inner panels, 6016 alloy in skin panels owing to paint bake hardening
Applications of wrought alloys 3XXX and 1XXX alloy panels Corrugated roof sheet Face panels Sanwich panels
Applications of wrought alloys 6XXX alloys High corrosion resistance and formability Various profiles
Wrought aluminium alloys Non heat treatable aluminium alloys Solid solution and deformation strengthening to increase strength 1XXX: >%99 Al conductors; structural applications in chemical and construction sectors 3XXX: Al-Mn Beverage cans and auto radiators 5XXX: Al-Mg Automotive structural applications (body panels)
Wrought alloys Heat treatable aluminium alloys Precipitation hardening to increase strength 2XXX: Al-Cu-Mg Aerospace panels 6XXX: Al-Mg-Si 7XXX: Al-Zn-Mg 8XXX: özel Extrusion profiles; automotive panels High strength structural applications 8001 (Al-Ni-Fe) nuclear plant structural applications
Heat treatable Non heat treatable Aluminium wrought alloys Alloy group main element Solid sol. hardening Deformation hardening 1xxx >99 Al 3xxx Mn 4xxx Si 5xxx Mg Precipitation hardening 2xxx Cu 6xxx Mg+Si 7xxx Zn 8xxx diğer
Temper designations XXXX-? F O H W T as fabricated annealed (softened in furnace!) hardened by deformation only for wrought alloys solutionized heat treated (other than F, O and H tempers)