LM4 datasheet
Aluminium Casting Alloy
(A1-Si5 Cu3 Mn0.5)

This Alloy Conforms To BS BS LM4 . BS1490:1988
Chemical Composition
  %Min % Max
Copper 2.0 4.0
Magnesium   0.20
Silicon 4.0 6.0
Iron   0.8
Manganese 0.2 0.6
Nickel   0.3
Zinc   0.5
Lead   0.1
Tin   0.1
Titanium   0.2
Aluminium   Remainder

Heat Treatment
This alloys response to Heat Treatment is dependant on the presence of Magnesium.
Therefore for such a treatment to be effective the Magnesium content should be at the maximum.

This alloy is widely used and is suitable for most general engineering purposes including cylinder heads, crank-cases, junction boxes, gear-boxes, clutch cases and switch gear covers where moderate mechanical properties are desirable.
Its casting characteristics permit it to be used for thick and moderately thin forms and where castings need to be pressure tight.
In the Heat-Treated state, it may be used for castings required to maintain a relatively high static loading. It has a good weldability

Mechanical Properties LM4-M LM4-TF
0.2% Proof Stress (N/mm²) 70-110 200-300
Tensile Stress (N/mm²) 140-170 230-290
Elongation (%) 2-3 0-2
Brinell Hardness 65-80 90-120
Shear Strength (N/MM2) 150 200