LM16

Aluminium Casting Alloy LM16

This alloy conforms to BS 1490:1988 LM16. Castings are standardised in the solution treated and naturally aged (TB) condition and in the fully heat treated (TF) condition.

Chemical Composition

	%		%		%
Magnesium	0.4-0.6	Copper	1.0-1.5	Iron	0.6 max
Silicon	4.5-5.5	Nickel	0.25 max	Manganese	0.5 max

Lead	0.1 max	Zinc	0.1 max	Titanium	0.2 max
Tin	0.05		Other each	0.05 max
Others total	0.15 max		Aluminium	Remainder

Mechanical Properties

	TB Sand Cast	TB Gravity Die Cast	TF Sand Cast	TF Gravity Die Cast
0.2% Proof Stress (N/mm²)	120-140	140-150	220-280	250-300
Tensile Strength (N/mm²)	170	230	230-290	280-320
Elongation (%)	2	3	0-1	0-2
Impact resistance Izod (Nm)	1.4	2.7	1.0	1.4
Brinell Hardness	80	85	100	110
Modulus of Elasticity (x10³ N/mm²)	71	71	71	71
Shear Strength (N/mm²)	-	-	200	235

Strength at Elevated Temperatures

LM16 retains its strength well, up to 200°C

Physical Properties


Coefficient of Thermal Expansion (per °C @ 20-100°C)	0.000023
Thermal conductivity (cal/cm²/cm/°C @ 25°C)	0.34
Electrical conductivity (% copper standard @ 20°C)	39
Density (g/cm³)	2.70
Freezing range (°C) approx.	620-550

Machinability

The heat-treated alloy has fairly good machining properties, but tools, which should preferably be of high speed steel, must be kept sharp. A moderately high rate of tool wear may be expected. Liberal cutting lubricant should be employed.

Corrosion resistance

The alloy has fairly good resistance to corrosion under atmospheric conditions.

Anodising

A protective film, usually greyish in colour, may be obtained by either the sulphuric or chromic acid process.

Heat Treatment

Full heat treatment gives high strength and hardness

Applications and General Notes

LM16 alloy is used for water-cooled cylinder heads, valve bodies, water jackets, cylinder blocks, fire hose couplings, air compressor pistons, fuel pump bodies, aircraft supercharger covers and similar applications where leak-proof castings having the high strength produced by heat treatment are required.

It is equally suitable for sand casting and for gravity die casting. LM16 has good weldability.

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