L M 24 is essentially a pressure diecasting alloy which conforms to BS 1490 1988 and is the most widely used of the sconary aluminium casting alloys manufactured by Brock Metal.
LM 24 is a general-purpose alloy suitable for high volume precision diecastings. This alloy offers excellent casting characteristics and good mechanical properties that make it ideal for engineering and functional parts, being ideally suited for the manufacture of thin wall sectioned castings. LM 24 offers excellent pressure retention properties and similar machining characteristics to other pressure diecasting alloys, but should not be specified where high resistance to corrosion is a critical requirement. The surfaces of LM 24 castings are not generally suitable for decorative anodising but other decorative finishes can be achieved easily.
It should be noted that pressure castings are not normally suitable for heat treatment. LM 24 retains its ambient temperature tensile strength up to approximately 150°C but a 50% loss in these figures should be anticipated at around 250°C.
The composition of this alloy is typical of that used throughout Europe and the United States of America.
| France | Germany | Italy | USA | Japan | Australia |
|---|---|---|---|---|---|
| A-S9U3A-Y4 | G-AlSi8Cu3 | UNI 5075/3601 | A380 | AC4B/ ADC10 |
CA3134/ BA323/AA325 |
| Alloy Destination | Al Si 8Cu 3.5 | Colour Code | Red + Blue |
| Short Destination | LM 24 | Alloy Number | N/A |
| Chemical composition of ingots. BS 1490 1988 | ||||||||||||
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Cu | Si | Mg | Fe | Mn | Ni | Zn | Pb | Sn | Ti | Others | Total | |
| Minimum | 3.0 | 7.5 | - | - | - | - | - | - | - | Each | - | - |
| Maximum | 4.0 | 9.5 | 0.3 | 1.3 | 0.5 | 0.5 | 3.0 | 3.0 | 0.2 | 0.2 | 0.05 | 0.15 |
| Mechanical Properties (Supplied in diecast form) |
Minimum | Maximum |
|---|---|---|
| Tensile strength | 180 MPa | 320 MPa |
| 0.2% Proof stress | 100 MPa | 150 MPa |
| Impact Strength Charp | - | 3.4Nm |
| Elongation | 1.5% | 1-3% |
| Shear Strength | - | 195 MPa |
| Modulus of Elasticity x 103 | 71 MPa | 71 MPa |
| Fatigue Strength 5 x 108 cycles | 70 MPa | 138 MPa |
| Hardness BHN | 85 max | 85 max |
| Physical Properties | |
|---|---|
| Melting Range | 580 - 520°C |
| Density | 2.79g/cm3 |
| Coefficient of Thermal expansion per °C at 20-100°C | 0.000021 |
| Thermal Conductivity cal/cm2/°C at 25°C | 0.23 |
| Electrical Conductivity | 24% IACS |
| Electrical Resistivity | -- |
Content supplied by Brock Metal