LM4 Aluminium Alloy
Sand or gravity casting Aluminium alloy.
LM 4 is general-purpose sand or gravity casting alloy which conforms to BS 1490 1988 and is suitable for the manufacture of a wide range of Aluminium casting applications.
Application
LM 4 is widely used for a range of engineering applications where moderate stress is envisaged. Its casting characteristics make it ideal for castings of varying section thickness as it can cope with heavy and moderately thin sections. Castings manufactured from this alloy can be heat treated to improve the mechanical properties. The machining properties are better than the high silicon aluminium alloys and considerably improve with heat treatment. LM 4 can be considered where relatively high static loads are anticipated as creep extension at moderately elevated temperatures is modest. Tensile strength applicable at room temperature is largely retained up to about 200 0 C but falls to about 50% at 3000 C.
Corrosion resistance in normal atmospheric conditions is reasonably good and can be improved by anodising. Anodising will give a grey or lighter finish tone depending on the anodising process used, and may be affected by the condition of the casting and the casting techniques employed. LM 2 or 24 are often preferred to this alloy if the application aligns itself to the pressure diecasting process.
This alloy is similar to the following international specifications:
| France | Germany | Italy | USA | Japan | Australia |
|---|---|---|---|---|---|
| A-S5U3 | G-AlSi6Cu4 | UNI 3052 | A 319 | AC 2A | AA 303 |
| Alloy Designation | Al Si 5Cu 3 | Colour code | Red. |
|---|---|---|---|
| Short designation | LM 4 | Alloy Number. | N/A |
| Chemical composition of Ingots. BS 1490 1988 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cu | Si | Mg | Fe | Mn | Ni | Zn | Pb | Sn | Ti | Others | Total | |
| Minimum | 2.0 | 4.0 | Each | |||||||||
| Maximum | 4.0 | 6.0 | 0.20 | 0.8 | 0.6 | 0.3 | 0.5 | 0.1 | 0.1 | 0.2 | 0.05 | 0.15 |
| MECHANICAL PROPERTIES | ||
|---|---|---|
| Supplied in diecast form. | Minimum | Maximum |
| Tensile strength | 160 MPa | 220 MPa |
| 0.2% Proof Stress | 80MPa | 110 MPa |
| Impact strength Charpy | -- | 2.1 Nm |
| Elongation | 2 % | 4 % |
| Shear strength | -- | 165 MPa |
| Modulus of Elasticity x103 | -- | 71 MPa |
| Fatigue Strength 5 x 108 cycles | -- | 85 MPa |
| Hardness BHN | 70 max | 90 max |
| PHYSICAL PROPERTIES | |
|---|---|
| Melting range | 625 - 525° C |
| Density | 2.75g / cm3 |
| Coefficient of Thermal expansion | 0.000021 |
| Thermal Conductivity | 0.29 |
| Electrical Conductivity | 32 % IACS |
| Electrical Resistivity | -- |
