Table 1: Aluminum Alloying elements and their properties

Element Effect
Boron
  • grain refiner
  • improves conductivity by precipitating vanadium, titanium, chromium, and molybdenum.
Copper
  • Promotes solution heat treatment
  • increase strength and hardness
  • decrease elongation
  • increses resistance to stress-corrosion cracking
Lead
  • improves machinability
Manganese
  • high strength in the work-hardened condition
  • high resistance to corrosion
  • good welding characteristics
  • increases the tendency to crack during hot rolling
  • makes aluminum alloys easier to cast
Magnesium
  • increased strength without unduly decreasing ductility
  • corrosion resistance
  • good weldability
  • increased tendency to crack during hot rolling
Silicon
  • Precipitation upon age hardening
  • produces Mg2Si precipitates
  • mold release properties for die casting
Zinc
  • susceptibile to stress-corrosion cracking
  • Magnesium and zinc form MgZn2
Zirconium
  • form a fine intermetallic precipitate that inhibits recovery and recrystallization.
  • controls the grain structure in wrought products

Wrought Aluminum Alloy Classification

The term "wrought aluminum" refers to aluminum alloys that have been mechanically worked to improve the grain structure an physical properties. Wrought aluminum is in a form of sheet, foil, plate, rod, bar, or tubing and it leaves the mill in the "as formed" condition. This also includes forms such as extrusions, and some forgings. The transformation from ingot to wrought product gives the material its final stated properties. The forming operations, thermal treatments, and/or aging transform the cast ingot's metallurgic property and crystalline structure. This strongly influences the strength, corrosion resistance, and several other properties of the finished product.

Aluminum classification numbering system has been established by American National Standards Institute (ANSI) and the Aluminum Association (AA). This classification system uses an alpha-numeric code to identify major alloying element and heat treating condition of the material. The primary alloy groups are designated by a four digit code. The first digit indicates the major alloying element as shown in the table below.

Table 1: Wrought Aluminum major alloying elements code

number alloy properties
1xxx Aluminum (99% minimum purity)
  • ductile
  • easily formed
  • corrosion resistant
2xxx Aluminum - Copper alloys
  • This is the most common heat treatable alloy.
  • aluminum-copper alloys respond to solution heat treatment
  • subsequent aging will increase strength and hardness while decreasing elongation.
3xxx Aluminum - Manganese alloys
  • Manganese increases strength either in solid solution or as a finely precipitated inter-metallic phase.
  • It has no adverse effect on corrosion resistance.
4xxx Aluminum - Silicon alloys
  • Most of aluminum-silicon wrought alloys are not heat-treatable (except alloy 4032 containing 1% of magnesium and alloy 4145 containing 4% of copper).
5xxx Aluminum - Magnesium alloys
  • Aluminum-magnesium alloys are not heat-treatable
  • may be strengthened by cold work (strain hardening)
  • Effectiveness of cold work hardening increases when magnesium content is increased.
  • Alloys of this series have moderate to high mechanical strength combined with relatively high ductility in annealed condition (up to 25%), good corrosion resistance and weldability.
6xxx Aluminum - Magnesium and Silicon alloys
  • Precipitation upon age hardening forms Guinier-Preston zones and a very fine precipitate.
  • Both of these increase the strength of these alloys
7xxx Aluminum - Zinc alloys
  • Aluminum-zinc alloys containing other elements offer the highest combination of tensile properties in wrought aluminum alloys.
8xxx Aluminum - Other Aluminum alloys
  • Aluminum-lithium alloys were developed for reducing weight in aircraft and aerospace structures.
  • Aluminum-lithium alloys are heat-treatable.
9xxx Aluminum - Unused

The second digit indicates modifications to the alloy formulation. When a new alloy is first introduced, the second digit is zero. Later if modifications to the chemical composition are made, a sequential number of 1 through 9 is used to designate the modified alloy. Within the 1xxx Aluminum group, a zero in the second digit indicates there is no special control on individual impurities. Digits other than zero indicate the number of impurities that are specifically controlled.

The last two digits are used as a commercial identifier for alloys within the group. Withing the 1xxx alloy group, the last two digits indicate specific minimum aluminum content. Although the absolute minimum aluminum content in this group is 99%, some grades have higher purity. The last two digits represent the hundredths of a per cent over 99%.

Experimental alloys are designated within the major groups of the four digit system, but are prefixed by the letter X. The prefix is dropped when the alloy becomes standard. During development, and before they are designated as experimental, new alloys are identified by serial numbers assigned by their originators. Use of the serial number is discontinued when the X number is assigned.

The four digit alloy designation also includes a suffix to indicate the type of heat treatment, temper, or type of straining process used to impart mechanical properties to the alloy. The two categories of suffix are for alloys that are heat treated to obtain physical properties and alloys that obtain physical properties by stain hardening, aging and tempering.p>

Non Heat-Treatable Alloy Suffix

Temper designations for heat treated wrought aluminum alloys consist of suffixes to the numeric alloy designations that begin with the letter "H" For example, in 3003-H14, 3003 denotes the alloy and “H14” denotes the temper, or degree of hardness. The temper designation also reveals the method by which the hardness was obtained. The letter "H" is always followed by 1, 2, or 3 digits. If there is only a single digit after the H it indicates hardness. If there are two digits, it indicates the method of hardening and the hardness.

Table 2: Wrought Aluminum alloy temper suffix code

first digit tempering method
xxxx-H1x strain hardened
xxxx-H2x strain hardened and partially annealed
xxxx-H3x strain hardened and stabilized
second digit degree of hardness
xxxx-Hx2 1/4 hardness
xxxx-Hx4 1/2 hardness
xxxx-Hx6 3/4 hardness
xxxx-Hx8 full hardness
xxxx-Hx9 extra hardness
third digit temper modification
xxxx-Hxx1 indcates stress relieved stretched

Heat-Treatable Alloy Suffix

Heat treatable aluminum alloy have a suffix of "F" to indicate the material properties were obtained as fabricated. This is common on extruded or forged shapes. If the product has been annealed the suffix is the letter "O" .  Certain members of the 7xxx group of alloys are solution heat treated and spontaneously age harden at room temperature.  This is important with heat treated rivets used in aircraft manufacture.  These items will have a "W" suffix that includes a time before age hardening occurs.  Finally, products that are specially processed to obtain physical properties have a suffix of "T" with numerals indicating the heat treating process and temper.  The letter “T” is always followed by one or more digits. These digits indicate the method used to produce the stable tempers.

Table 3: Heat treated aluminum alloy suffix codes

suffix heat treatment, temper and post process
xxxx-T3   Solution heat treated, then cold worked.
xxxx-T351 Solution heat treated, stress-relieved stretched, then cold worked.
xxxx-T36  Solution heat treated, then cold worked (controlled).
xxxx-T4   Solution heat treated, then naturally aged.
xxxx-T451 Solution heat treated, then stress relieved stretched.
xxxx-T5   Artificially aged only.
xxxx-T51  Solution heat treated, then stress relieved stretched, no straightnening
xxxx-T510 Solution heat treated, then stress relieved stretched, no straightnening
xxxx-T511 Solution heat treated, then stress relieved stretched, straightnened after stretching
xxxx-T6   Solution heat treated, then artificially aged.
xxxx-T61  Solution heat treated (boiling water quench), then artificially aged.
xxxx-T651 Solution heat treated, stress-relieved stretched, then artificially aged (precipitation heat treatment).
xxxx-T652 Solution heat treated, stress relieved by compression. then artificially aged.
xxxx-T7   Solution heat treated, then stabilized.
xxxx-T8   Solution heat treated, cold worked, then artificially aged.
xxxx-T81  Solution heat treated, cold worked (controlled), then artificially aged.
xxxx-T851 Solution heat treated, cold worked, stress-relieved stretched, then artificially aged.
xxxx-T9   Solution heat treated, artificially aged, then cold worked.
xxxx-T10  Artificially aged, then cold worked.

Common wrought aluminum alloys and properties

1100 This grade is pure aluminum. It is soft and ductile with good workability and can be polished to a mirror finish. It is ideal for applications involving intricate forming because it does not work harden as quickly as other alloys. This makes it ideal for foils and lithography plates. It is the most weldable of aluminum alloys, by any method. This grade can not be heat treated. It has excellent corrosion resistance and is widely used in the chemical and food processing industries and other uses where product purity is important. It responds well to embossed designs and finishes. Ductile enough for deep draws, but the lowest strength aluminum alloy. Uses include light reflectors, decorative and jewelry parts, name plates. Seldom used in precision sheet metal stampings.

2011 This is the most easily machined aluminum alloy. It also has excellent mechanical properties. Thus, it is widely used for automatic screw machine products and in parts requiring extensive machining.

2014 & 2017 These two alloys have excellent machinability and high strength 2014 has slightly higher tensile strength. It is a tough, ductile alloy suitable for heavy-duty structural parts and it's used in a wide variety of screw machined and billet parts.

2024 This is one of the most common high strength aluminum alloys. With its high strength and excellent fatigue resistance, it is used in applications where a high strength-to-weight ratio is desired. It is easily machined to a high finish. It can be forged or formed in the annealed condition, then heat treated for maximum strength and fatigue resistance. This alloy is not considered weldable, but may be spot, capacitive discharge, or seam welded. This alloy is usually anodized to provide corrosion protection or manufactured with a pure aluminum cladding (Alclad). This alloy is primarily used in aerospace industry for aircraft components, fittings, and hardware, Other uses include automotive wheels and other parts for the transportation industry.

3003 This is a general purpose manganese alloy that is the most widely used of all aluminum alloys. The addition of Manganese increases its' strength by 20% over the 1100 grade. This combines the excellent characteristics of 1100 with higher strength. It has excellent corrosion resistance. It has excellent workability and it may be deep drawn or spun. It can welded by all conventional processes. Like 1100, it also can not be heat treated. This alloy is commonly used to make cooking utensils, decorative trim, mail boxes, awnings, siding, storage tanks, and window frames lithography plates.

5005 This alloy is generally considered to be an improved version of 3003. It has the same general mechanical properties as 3003 but appears to stand up better in actual service. It is readily workable. It can be deep drawn or spun. It is weldable by all conventional processes. It has excellent corrosion resistance. It is non heat-treatable. It is well suited for anodizing and has less tendency to streak or discolor. It is used in many of the same applications as 3003.

5052 The main alloying element in this grade is magnesium. This makes it far stronger than any of the alloys described above, yet forms well with reasonable bend radii. This is the highest strength alloy of the more common non heat-treatable grades. Fatigue strength is higher than most aluminum alloys. In addition this grade has particularly good resistance to marine atmosphere and salt water corrosion. It has excellent workability. It may be drawn or formed into intricate shapes and its slightly greater strength in the annealed condition minimizes tearing that occurs in 1100 and 3003. Applications include a wide variety of home appliances, marine and transportation industry parts, heavy duty cooking utensils and equipment for bulk processing of food. Corrosion resistance and weldability are very good. It has better salt water corrosion resistance than 1100. 5052 is commonly used for electronic chassis, tanks, pressure vessels and any number of parts requiring considerable strength and formability at reasonable cost. Anodizing may be slightly yellowish.

5083 & 5086 For many years there has been a need for aluminum sheet and plate alloys that could be used for high strength welded applications. This alloy has several distinct benefits over such alloys as 5052 and 6061. Some of the benefits are greater design efficiency, better welding characteristics, good forming properties, excellent resistance to corrosion and the same economy as in other non heat-treatable alloys. Metallurgical researchers developed 5083 and 5086 as superior weldable alloys to fill these requirements. Both alloys have virtually the same characteristics with 5083 having slightly better mechanical properties due to higher manganese content. It is commonly used in unfired pressure vessels, missile propellant and oxidizer tanks, heavy-duty truck and trailer assemblies, boat hulls and superstructures.

6061 & 6063 This material is an alloy of magnesium and silicon. It is the most common material for extrusions and is the least expensive and most versatile of the heat-treatable aluminum alloys. It has most of the good qualities of aluminum. It offers a range of good mechanical properties and good corrosion resistance. It can be fabricated by most commonly used techniques. In the annealed condition it has good workability although it requires greater bend radii than 5052. In the T4 condition fairly severe forming operations may be accomplished. The full T6 properties may be obtained by artificial aging. It is welded by all methods and can be furnace brazed. It is available in the clad form (Alclad) for better appearance and corrosion protection. Applications include a wide variety of products from truck dump bodies and frames to screw machine parts and structural components and some marine applications.

6063 This grade is commonly referred to as the architectural alloy. It was developed as an extrusion alloy with relatively high tensile properties, excellent finishing characteristics and a high degree of resistance to corrosion. This alloy is most often found in various interior and exterior architectural applications, such as windows, doors, store fronts and assorted trim items. It is the alloy best suited for anodizing applications - either plain or in a variety of colors.

7075 This is one of the highest strength aluminum alloys available. Its strength-to weight ratio is excellent and it is ideally used for highly stressed parts. It may be formed in the annealed condition and subsequently heat treated. Spot or flash welding can be used, although arc and gas welding are not recommended. It is available in the clad (“Alclad”) form to improve the corrosion resistance with the over-all high strength being only moderately affected. Applications: Used where highest strength is needed.

7475 This is a superplastic-formable high-strength aluminum alloy, now available for structural applications and designated. Strength of alloy 7475 is in the range of aerospace alloy 7075, which requires conventional forming operations. Although initial cost of 7475 is higher, finished part cost is usually lower than that of 7075 because of the savings involved in the simplified design/assembly.

8090 is a class of aluminum-lithium alloys possess increased Modulus of Elasticity, high specific stiffness, increased fatigue strength and cryogenic strength. Alloys, containing silver, have also good weldability. Zirconium is added to aluminum-lithium alloys for controlling grain structureduring heat treatment. Aluminum-lithium alloys are used for manufacturing aircraft structures, aerospace vehicle skins, spacecraft fuel tanks (liquid Hydrogen and oxygen).

Cast Aluminum Alloy Classification

Aluminum can be ‘cast’ by every process used in metal casting. These processes, in descending order of quantity of aluminum casting are: die casting, permanent mold casting, sand casting, plaster casting, investment casting, and continuous casting. The casting process is selected based on factors such as cost, feasibility, quality of parts, etc. For instance, large products are made using sand casting. The quality factor is also important in selecting the casting process. Quality refers to both, mechanical properties (ductility and strength) and soundness (surface imperfections, cracking, and freedom from porosity).

The process of die casting utilizes almost two times the tonnage of aluminum alloys as the combination of other casting processes. Die casting is best suited for large quantity production of relatively small parts. Aluminum die castings up to 50 Kg can be produced if casting-machine costs and high tooling are justified.

Aluminum casting alloys are based on the same alloy system of thouse in the wrought categories.  They are strengthendby the same mechanisms, except strain hardening. and are similarly classified into hon heat treatbele and heat treatable type.s  The major difference is that the casing alloys usind in the geatest volumes contin allioying additions of silicon far in excess of the amounts in most wrought alloys.  Silicon is the allouning element that literally makes the commercial viability of the high volume aluminum cating industry possible. silicon contents from 4 to the eutectic level of 12 reduce scrap losses, permit production of more intricate designs with greater variations in section thickness and yield castings with highter surface and internal qualities.  These benefits are from the effects of silicon in icreasing fluidity, reducing cracking, and improving feeding to minimize shrinkage porosity

Die cast 380 aluminum has a higher tensile strength than gray cast iron yet only half the mass. There are a wide variety of aluminum alloys with various tensile strength, corrosion resistance, and heat treatments. Most easily cast alloys tend to be soft and have relatively low yield strength.  In the past, aluminum was mostly processed into form by the method of sand casting. Since the material cost was high, the cheapest available alloys were often used. It is some of these cheap cast alloys that have given this material an undeserved reputation. When aluminum is die cast, better alloys may be used that have remarkable characteristics. Small NEMA Motor endshields are die cast, 380 aluminum with a tensile strength of 48,000 psi. Compare this with soft gray cast iron that has 20,000 to 25,000 psi tensile strength.

The alloying system for aluminum uses a rational numbering system.  UNS and the Aluminum Association (AA) parallel each other in their numbering system.  For example, AA designates A356.0, UNS uses A13560. The AA numbering system is the most commonly used in the United States. It was adopted by AA in 1954 and approved by ANSI in 1957 (ANSI H35.1)  The American Society for Testing and Materials (ASTM), the Society of Automotive Engineers (SAE), and the Federal and Military specifications for aluminum castings conform to the AA designation system.

Cast Aluminum Numbering System

The first digit is an alpha indicator of base metal. Always A for aluminum in the UNS system.  The AA system uses the alpha character to distignuish between alloys that differ only slightly in percenages of impurities or minor alloying elements.  The alpha character can be A356.0, B356.0, F356.0 are common examples.

Table 5: Second Digit: Casting Alloy Designation

first
digit
primary element reason
Axxx.x Aluminum always the letter A to designate Aluminum
second
digit
alloy elements properties
A1xx.x 99% pure Aluminum  
A2xx.x Aluminum-Copper alloy capable of developing highest strengths among all castion alloys.  Good casting design and foundary techinques must be used to get full mechanical properties and consistent high quality parts.  Good high temperature strenght. Heat treatment is required with these allys.  Lower corrosion resistance and surface protection is required in critical applications
A3xx.x Aluminum-Silicon alloy with Copper and/or Magnesium low cost, highest volume usage.  Three main types Al-Si-Mg, Al-Si-Cu or Al-Si-Cu-Mg.  Those with copper are heat treatable. both copper and magnesium increase strenght and hardness in the as cast (f) temper and at elevated temperatures.  Arificial aging treatments
A4xx.x Aluminum-Silicon alloy based on the binary aluminum-silicons system and contain 5-12% SILICON.  mODERATE STRENGHT AND HIGH DUCTILITY IMPACR RESISTANCE
A5xx.x Aluminum-Magnesium alloy moderate to high strength and toughness.  High corrosion resistance especiall to sea water and marine atmospheres. can be welded and good machinability, anodized
A6xx.x unused  
A7xx.x Zinc  good finishing characteristics, good corrosion resistance. capable of high strenght through natural aging without heat treatment
A8xx.x Tin conatin 6%tin and small amounts of copper and nickel for strength.  These alloys were developed for bearing applications.  Tin imparts lubricity.
A9xx.x Other  
third&fourth
digits
alloy designation charactreristics
A319.x commercial code low cost Silicon-Copper alloy
A360.x   corrosion resistant
fifth
digits
specification type of specification
Axxx.0 casting casting specification
Axxx.1 ingot ingot specification
Axxx.2 ingot more tightly refined ingot specification

Some common casting alloys and their properties

A242 alloy is used extensively for applications where strength and hardness at high temperature are required. This alloy has good fluidity and shows resistance to hot cracking and shrinkage in the casting process. It has satisfactory weldability by arc and resistance methods but brazing is not recommended. Typical applications include: motorcycle, diesel, and aircraft engine pistons, aircraft generator housings, as well as air cooled cylinder heads.

A319 alloy exhibits good casting qualities including pressure tightness and moderate strength. It has good weldability and corrosion resistance. The casting and mechanical properties are not largely affected by fluctuations in impurity content. The main casting method for this alloy is sand casting. The uses include internal combustion and diesel engine crankcases. oil tanks and oil pans. It is also used in permanent mold casting with applications including water-cooled cylinder heads, rear axle housings and engine parts.

A356 aluminium alloys are characterized by very good mechanical properties and low porosity with a globular microstructure which is fine and uniform. The mechanical properties can be further improved through heat treatments such as T5 and T6. These alloys are used for casting general-purpose die castings. The common alloys used are 356-T6 for cast wheels. A356 has largely been replaced by 295 used in permanent mold castings for machine tool parts, aircraft wheels pump parts, tank car fittings, marine hardware, valve bodies, and bridge railing parts.

A360.0 is specified for die cast parts that require good corrosion resistance Special alloys for special applications are available, but their use usually entails significant cost premiums. This alloy is commonly found in applications such as frying pans, instrument cases, cover plates, and electronic component frames.

367.0 & 368.0 The Aluminum Association has designated two of these strontium containing Al-Si alloys developed by Mercury. 367.0 is used in all die cast L6 and L4 Verado drive shaft housings because 367.0 has nearly three times the impact energy of the typical die casting alloy. In addition, all swivel brackets that used to be made in A356-T6 are now made in 367-T6. Thus, the biggest and most critical parts, that must withstand two 40 miles per hour impacts on the gear case housing (also called the lower unit) without falling, have been converted to this alloy. 368.0 is used in all of Mercury's die cast boat propellers. The Al-Si alloy 368.0 replaced the single phase, Al-Mg 515 alloy that was used in boat propeller production for over 25 years because 368.0 had significantly higher strength and better ductility.

A380.0 is one of the most common general purpose die casting alloys. It has high tensile strength and is easily cast into intricate and large shapes. Components made from A380 have fair weldability, but brazing is not recommended. Generally, this alloy is machined with carbide tooling due to the abrasive silicon content of the alloy. Tools should be sharp with high rake and clearance angles.  Machines should be operated at moderate to high feeds and speeds to minimize tool wear. 380 provides the best combination of utility and cost. Some common applications of die cast parts using this alloy include lawn mower housings, streetlamps housings, dental equipment, air brake castings, gear cases and automatic transmission housings.

383 & 384 These alloys are a modification of 380. Both provide better die filling, but with a moderate sacrifice in mechanical properties, such as toughness.

A390 This alloy is hypereutectic aluminum-silicon alloy. The optimum structure of it must consist of fine, uniformly distributed primary Si crystals in a eutectic matrix. This alloy does not require heat treatment. The low coefficient of thermal expansion, high hardness and good wear resistance of these alloys make them suitable for internal comustion engines, pistons and cylinder blocks. A390 is often Selected for special applications where high strength, fluidity and wear-resistance/bearing properties are required.

413 Used for maximum pressure tightness and fluidity for complicated shapes in critical applications. A413.0 is commonly used for outboard parts of motor like connecting rods, pistons, housings.

514 This alloy has a relatively poor fluidity and a high degree of directional solidification shrinkage. High pressure die casting is the primary method of forming this alloy. This combination of material properties make 514 less casting friendly. As a result careful attention to casting geometry is essential. Because of its poor fluidity, fine detail and thin sections are difficult and radii must be large Because of shrinkage, feeding the casting requires large risers proper design. High ductility and excellent corrosion resistance is the main advantage of this alloy. It is commonly found boat propellers where impact toughness is required.

A518.1 for conveyor components, escalator parts, aircraft, marine hardware.

A535.0 is an aluminum-magnesium alloy with good combination of strength, shock resistance and ductility.  It is used for parts in instruments and tools where dimensional stability is a prime factor. This alloy doesn't require heat treatment. It is used in parts that need strength and stability like impellers, optical equipment. It can be polished and anodized. It has excellent machining properties and an exceptional finish can be produced, especially when machined with carbide tools at maximum speeds. It is highly resistant to corrosion and will not need any futher surace treatment for most applications. It is weldable in an inert gas or shieded arc methods.

A712 is employed when a combination of good mechanical proterties without heat treatment is needed.  It shows good shock and corrosion resistance.  Machinability and dimensional stability are also good.  No distortion is exhibited when A712.0 is heated.  After brazing the alloy wil regain its natural strenght by aging. it has fair to good castibiliity although pressure tightness and resistance to hot cracking are only fair.

713 This alloy.

Process considerations


Permanent Mold Casting Aluminum Alloys

Permanent mold casting is best suited for high-volume production. Their size is larger than die castings. These castings have a very low pouring rate. They are gravity-fed. Outstanding mechanical properties are exhibited by permanent mold castings. There is a lot of scope for further improvement if they are given heat treatment.

Some of the most common alloys of permanent mold casting include Alloy 366.0 for automotive pistons, Alloys 355.0, A357.0, C355.0 for impellers, timing gears, compressors, missile and aircraft components, Alloys A356.0, 356.0 for aircraft wheels, parts of pump parts, valve bodies, marine hardware, and 296.0, 333.0, 319.0.

Sand Casting Aluminum Alloys

This type of casting involves formation of casting mold (with sand). It is inclusive of conservative sand casting & lost-foam casting. The first one involves forming a pattern of sand, pouring the molten metal into it and breaking it once the product is formed. Lost-foam pattern involves putting a dispensable pattern of polystyrene in the mold. The rest of the procedure is the same as conservative sand casting.
 

Die Casting Aluminum Alloys

Aluminum die casting alloys  are lightweight, offer good corrosion resistance, ease of casting, good mechanical properties and dimensional stability.  Although a variety of aluminum alloys made from primary or recycled metal can be die cast, most designers select standard alloys such as A380

In high pressure die casting, which accounts for nearly 70% of all cast aluminum products made in the United States, it is the convention to use approximately 1% iron in the alloy to avoid die soldering. Actually depending on the alloy, the iron specification can be 1.2%  max, or 1.5% max, or even 2.0% max.  these levels of iron seriously degrade the mechanical properties. Thus, the task of obtaining superior die casting mechanical properties is to find other ways of avoiding die soldering without the use of iron. Substituting manganese for iron is a partial solution. A far better solution is with the use of high levels of strontium, in the range 500 to 700 ppm, which apparently either increases the surface tension of aluminum or forms a surface oxide, or both, and avoids die soldering.  tension of aluminum and creating "non-wetting" conditions.

The die castings of aluminum alloys are generally produced using aluminum -silicon-copper alloys. This alloy family gives an excellent combination of corrosion resistance, strength, and cost, along with respite from ‘hot shortness’ and high fluidity which are mandatory for easy casting. If one desires a better resistance to corrosion, he should make use of alloys having a lower copper content.

Physical properties of alloys using various process

Table 6: Sand Casting (F-Temper).

Alloy Grade 319 356 514 535 713
tensile strength (1000psi) 23.0 19.0 22.0 35.0 32.0
yield strength 13.0 --- 9.0 18.0 22.0
Major Alloying Elements - normal %          
silicon % 6.0 7.0 --- --- ---
copper % 3.5 --- --- --- ---
magnesium % --- 0.3 4.0 7.0 ---
zinc % --- --- --- --- 7.5
Characteristics (1 is best)          
corrosion resistance 3 2 1 1 3
machinability 3 3 1 1 1
polishing 2 2 3 4 4
weldability 2 2 3 4 4
cost 1 2 4 4 4

Table 7 more properties.

Tensile Strength Yield Strength Elongation Hardness
    psi psi % in 2" (500 kg load)
--- 319 27,000 18,000 2 70
--- 319-T6 36,000 24,000 2 80
--- A356 23,000 12,000 6 70
--- A356-T6 40,000 30,000 6 75
--- 357.0 25,000 13,000 5 -
--- 357-T7 46,000 36,000 3 85
--- 535 40,000 20,000 13 70
--- 705 30,000 17,000 5 -
--- 713 32,000 22,000 3 75