LM2 Aluminium Alloy
Pressure diecasting Aluminium alloy.
L M 2 is essentially a pressure diecasting alloy conforming to BS 1490 1988, this alloy is often specified as an alternative LM 24 in pressure diecasting applications.
Application
LM 2 is a general-purpose alloy suitable for the manufacture of almost any diecast part. It is often specified on large volume diecast applications in preference to LM 24 because of its lower density. By implication this means that applications for this alloy are quite wide and varied. Service conditions which dictate high corrosion resistance or higher than usual ductility would normally require an alternative alloy.
The chemistry present has a marked effect on the mechanical properties achieved; low levels of copper, nickel and manganese reduce the strength at temperatures above 2500 C. For this reason it is advisable to restrict the service conditions to a maximum of 1500 C. Corrosion resistance is inferior to LM 6 but use in normal atmospheric conditions is acceptable. Anodising of LM 2 castings is possible, but only on decorative finishes, as a grey film will result.
LM 2 castings are not normally heat-treated but annealing is possible to improve ductility.
The high silicon levels present in this alloy mean that machining can be marginally difficult and result in excessive tool wear. The copper element does mean that drag during machining is reduced making this alloy easier to machine than LM 6 or 20. Castings made from LM are not suitable for welding or brazing.
The composition of this alloy is typical of that used throughout Europe and the United States of America.
| France | Germany | Italy | USA | Japan | Australia |
|---|---|---|---|---|---|
| AS 9U3-Y | UNI 5076 | AA384 | ADC12 |
| Alloy Designation | Al Si 10Cu | Colour code | Red + white. |
|---|---|---|---|
| Short designation | LM 2 | Alloy Number. | N/A |
| Chemical composition of Ingots. BS 1490 1988 | ||||||||||
|---|---|---|---|---|---|---|---|---|---|---|
| Cu | Si | Mg | Fe | Mn | Ni | Zn | Pb | Sn | Ti | |
| Minimum | 0.7 | 9.0 | ||||||||
| Maximum | 2.5 | 11.5 | 0.30 | 1.0 | 0.5 | 0.5 | 2.0 | 0.03 | 0.2 | 0.2 |
| MECHANICAL PROPERTIES | ||
|---|---|---|
| Supplied in diecast form. | Minimum | Maximum |
| Tensile strength | 150 MPa | 300 MPa |
| 0.2% Proof Stress | 90MPa | 130 MPa |
| Impact strength Charpy | -- | 2.9Nm |
| Elongation | 1% | 3% |
| Shear strength | -- | 200MPa |
| Modulus of Elasticity x103 | 71 MPa | 71 MPa |
| Fatigue Strength 5 x 108 cycles | -- | 71 MPa |
| Hardness BHN | 65 max | 90 max |
| PHYSICAL PROPERTIES | |
|---|---|
| Melting range | 570- 525° C |
| Density | 2.74g / cm3 |
| Coefficient of Thermal expansion | 0.00002 |
| Thermal Conductivity | 0.24 |
| Electrical Conductivity | 26 % IACS |
| Electrical Resistivity | -- |
