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LM9

Aluminium Casting Alloy LM9

This alloy conforms to BS:1490 1988 LM9. Castings are standardised in the as cast (M) condition, in the precipitation treated (TE) condition or in the fully heat treated (TF) condition.

Chemical Composition

  %   %   %
 Copper  0.2  Magnesium  0.2-0.6  Silicon  10.0-13.0
 Iron  0.6  Manganese  0.3-0.7  Nickel  0.1 max
 Zinc  0.1  Lead  0.1 max  Tin  0.05 max
 Titanium  0.2  Aluminium  Remainder  Others each  0.05 max
 Others total  0.15 max        

 

Mechanical Properties of Aluminium (Sand & Die Casting) Alloy LM9

 

M Gravity Die Cast

TF Sand Cast

TF Gravity Die Cast

TE Sand Cast

TEGravity Die Cast

0.2% Proof Stress (N/mm2)

95-120

220-250

270-280

110-130

150-170

Tensile Strength (N/mm2)

190

240

295

170

230

Elongation (%)

3-5

0-1

0-1

1.5

2

Impact Resistance Izod (Nm)

-

0.7

1.4

1.4

2

Brinell Hardness

75-85

95

110

70

85

Modulus of Elasticity (103 N/mm2)

-

71

71

71

71

Shear Strength (N/mm2)

-

200

230

120

160

Strength at Elevated Temperatures

Tensile properties are unaffected by temperatures up to 150°C but prolonged heating at temperatures significantly higher reduces the strength. For example, the tensile strength of chill cast LM9-TF at 200°C (after heating for 500h) is approximately half that at room temperature, and only 25% of the original value at 250°C.

Physical Properties of Aluminium (Sand & Die Casting) Alloy LM9

 

 

Coefficient of Thermal Expansion (per °C @ 20-100°C)

0.000022

Thermal conductivity (cal/cm2/cm/°C @ 25°C)

0.35

Electrical conductivity (% copper standard @ 20°C)

38.0

Density (g/cm3)

2.68

Freezing range (°C) approx.

575-550

Machinability

Very considerable tool wear occurs in machining this aluminium alloy, but there is not the same tendency to drag that occurs with high Silicon alloys containing no other alloying elements, e.g. LM6. Carbide-tipped tools with large rake angles and relatively low cutting speeds give good results. A cutting lubricant and coolant should be employed.

Corrosion Resistance

LM9 exhibits excellent resistance to corrosion under both ordinary atmospheric and marine conditions.

Anodising

LM9 Can be anodised by any of the common processes, the resulting protective film ranging in colour from grey to dark brown, depending on the method employed.

Heat Treatment

Heat Treatment produces high strength and hardness
 

Applications and General Notes

LM9 alloy is used where the fluidity and corrosion resistance of LM6 are required with high strength and hardness. It is equally suitable for sand casting and gravity die casting and is extensively used for low pressure castings, for cover plates and instrument cases. It is useful for electroplated components. LM9 has poor weldability and brazeability.

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