Here is a slide, which introduces basic information about cast aluminum alloys, how to name each alloy, selection rules, some example regrading of alloys from each group and their properties. Hope you find it interesting and helps you in any way possible.

1. Cast Aluminum Alloys

2. Aluminum alloys favorable
characteristics
· Good fluidity
· Low melting point
· Rapid heat transfer from the molten aluminum to the
mold
· Hydrogen is the only gas with appreciable solubility in
aluminum and its alloys and it can be removed with
several methods.
· Free from hot-short cracking and tearing tendencies
· Chemical stability

3. Cast Alloy Designations
No single universally accepted designation
system
Designations systems include:
 US 3 digit number, plus 1 decimal
 EN 5 digit number (RSA standard since1990’s)
 Chemical designations (eg old DIN)
 UK discontinued LM series still commonly
cited in RSA
 Others – eg old eastern Europe
 Others Far East – including Japan

4. Aluminum Casting Designations
Cast Alloy Designation (US)
US 3 digit number, plus 1 decimal
Al+
Pure Al Cu Si/Cu/Mg Si Mg Zn Sn
Other
1xx.x 2xx.x 3xx.x 4xx.x 5xx.x 7xx.x 8xx.x 9xx.x
Non-heat-treatable
Heat-treatable

5. AXXX.XIndicates a modification of the
original alloy or an impurity
limit ( Starting with A)
Aluminium Casting Designations
Cast Alloy Designation (US)
Principle Alloying Element
Specific alloy of the family
(Except for 1xx.x series)
Product Form - Final Casting (.0) or Ingot (.1 or .2)*
*Depending on Purity Limits

6. Example
Alloy A356.0 represents :
A finished casting (xxx.0)
Silicon plus copper and/or magnesium serie
(3xx.x)
Tighter controls on iron and other
impurities(Axxx.x)

7. Non-heat-treatable and Heat-treatable Alloys
Heat treatable Alloys Non heat treatable
Alloys
2xx.x 1xx.x
3xx.x 4xx.x
7xx.x 5xx.x
8xx.x
9xx.x

9. or without
O: annealed. The O applies to cast products that are
annealed to improve ductility and dimensional stability

11. Cast alloy designation system

12. 2xx.x series (Aluminum-Copper)
× Poor castability
× Poor corrosion resistance
× High specific gravities
So Al-Cu cast alloys have been replaced by
Al–Si–Mg alloys
Heat treatable
Capable of developing the highest strengths among all cas
alloys through heat treating
Highest strengths and hardnesses of all casting alloys at
elevated temperatures (to 300 °C)

13. Example
242 ( 4% Cu , 2% Ni & 1.5% Mg )
Has high strength at elevated temperatures due to addition o
nickel and magnesium
Application
Internal combustion engine pistons

14. 3xx.x series
(Aluminum-Silicon, with added copper and/or
magnesium)
In addition to silicon, contain magnesium, copper, or both
(Al-Si-Mg, Al-Si-Cu, or Al-Si-Cu-Mg)
Highest-volume-usage alloys
Silicon contents range from 5% to 22%
Copper contents range from 0% to a maximum of 4.5%
Magnesium contents ranging from as low as 0.3% to 0.6%

15. Increase in strength and hardness in the as cast (F) tempe
through solid-solution hardening both copper and magnesiu
Much greater Increases afforded by T5 tempers or by T6 o
tempers
Precipitation hardening results from precipitate structures
based on Mg2Si, Al2Cu, Al2CuMg, or combinations of these
phases.
Thermal expansion coefficient decreases with increasing
silicon
beneficial for engine applications such as pistons
Enhancing wear resistance when Silicon content exceeds
12%,
as in alloys 390.0 through 393.0 by primary silicon
3xx.x series

16. Example
356 Alloy
Application : Aircraft wheels
7% Si for enabling castablilty
0.35% Mg for enabling heat treatability
Mg2Si responsible for precipitation hardening
 Addition of Na in order to :
1. Refine eutectic structure
2. Improvement in mechanical properties
3. Less micro-shrinkages between dendrites

17. Without modification With modification
S
i
S
i

18. 4xx.x series (Aluminum-Silicon
High fluidity
Excellent feeding during solidification
Free from hot shortness
More corrosion resistance in acidic environments
Not considered heat treatable due to small solubility of Si in
Aluminum
A simple eutectic system

20. Examples
413
Contains 12% Si
Used in die casting
443
Contains 5.3% Si
Used in sand and permanent mold
castings

21. Solidification of 443(5% Si)
First solidification of almost pure Aluminum dendrites
Space between dendrites fills with Al-Si eutectic
As eutectic freezes, it decompose into pure Al and Si
Faster solidification rates result in smaller dendrites
cells

22. Sand cast Permanent mold cast
Die cast
Dendrites

23.  Addition of Na or Sr results in
1. Refining eutectic structure (less angular)
2. Improvement in mechanical properties
Aluminum-Silicon modification
Without Na With Na

24. Eutectic structure can also be refined with faster cooling
rates
Sand cast( slow cooling
rate) with and without Na
Chill cast

26. Typical mechanical properties of sand- , permanent-mold- and die-cast
Al alloys
Yield Strength, ksiTensile Strength,
ksi

27. Mn addition
Al-Si-Fe intermetallics

29. Selection of Casting Alloys
· Casting process considerations: fluidity, resistance to hot
tearing, solidification range
· Casting design considerations: solidification range, resist
to hot tearing, fluidity, die soldering (die casting)
· Mechanical-property requirements: strength and ductility,
Heat treatability, hardness
· Service requirements: corrosion resistance, surface treat
, dimensional stability, thermal stability
· Economics: machinability, weldability, ingot and melting c
heat treatment

30. Selection of Casting Alloys
1=best ,
5=lowest