BSL154 and B5L155 - Aluminium Casting Alloy

(Al-Cu4Sil)

This alloy conforms to British Standard L154 when solution treated and aged at room temperature and to British Standard L155 when solution treated and artificially aged.

Material supplied as standard 7kg aluminium ingot.

Chemical Composition

  %
Copper 3.8-4.5 max
Magnesium 0.10 max
Silicon 1.0-1.5
Iron 0.25 max
Manganese 0.1 max
Nickel 0.1 max
Zinc 0.1 max
Lead 0.05 max.
Tin 0.05 max
Titanium 0.05-0.25
Aluminium Remainder
Others: each 0.05 max.
Others: total 0.15 max.

The ingots and castings shall be grain refined with Titanium or with Titanium and Boron. The ingot maker shall declare the grain refining element(s) used.

Mechanical Properties

L154

  Sand Cast Chill Cast
0.2% Proof Stress (N/mm 2 ) 160 165
Tensile Stress (N/mm 2 ) 215 265
Elongation (%) 7 13
Impact Resistance Izod (Nm) - -
Brinell Hardness 70 80
Endurance Limit (5x10 7 cycles;N/mm 2 ) 50 50
Modulus of Elasticity (x10 3 N/mm 2 ) 71 71
Shear Strength (N/mm 2 ) 180 180

The specified values above may not be achieved until after 30 days at room temperature.

The grain size of the castings shall be as uniform as possible and preferably not greater than 0.20 mm. 

L154

  Sand Cast Chill Cast
0.2% Proof Stress (N/mm 2 ) 200 200
Tensile Stress (N/mm 2 ) 280 310
Elongation (%) 4 9
Impact Resistance Izod (Nm) - -
Brinell Hardness 85 85
Endurance Limit (5x10 7 cycles;N/mm 2 ) 50 50
Modulus of Elasticity (x10 3 N/mm 2 ) 71 71
Shear Strength (N/mm 2 ) 205 205

The grain size of the castings shall be as uniform as possible and preferably not greater than 0.20 mm.

The values in bold type are standardized properties for separately cast test samples produced to the requirements of BS 4L101; those in normal type are typical properties.

Strength at Elevated Temperatures

After a long duration at 200°C the strength drops to half of that at room temperature.

Physical Properties

   
Coefficient of Thermal Expansion (per°C at 20-100°C) 0.000023
Coefficient of Thermal Expansion (per°C at 20-200°C) 0.000024
Thermal Conductivity (cal/cm 2 /cm/°C at 25°C) 0.33
Electrical Conductivity (% copper standard at 20°C) 34
Density (g/cm 3 ) 2.80
Freezing Range (°C) approx 645-550

Machinability

The alloys have excellent machining characteristics, especially when fully heat-treated.

Corrosion Resistance

The alloy has moderate resistance to corrosion under atmospheric conditions.

Anodizing

Satisfactory films can be obtained by most processes but the sulphuric acid method gives the best results.

Casting Characteristics

  • FLUIDITY - Fair, not normally used for thin castings.
  • TIGHTNESS - Poor, unsuitable for leak tight castings.
  • HOT-TEARING - Poor. This alloy is susceptible to hot tearing, and this limits the alloy to being sand cast or cast in simple permanent moulds. Care should be taken with mould design to avoid constraints, and a more generous use of chills and feeders is required to ensure a good temperature gradient during the freezing process. This alloy has a long freezing range and may suffer from shrinkage porosity.
  • TYPICAL POURING TEMPERATURE - 680-700°C
  • PATTERNMAKERS' SHRINKAGE - 1.3% or 1/75. 

Heat Treatment

L154 (solution heat treated and aged at room temperature)-Heat for not less than 16 hours at 505-515°C, quench in water at a temperature of 50-70°C, or in a polymer quenchant not hotter than 30°C. The specified proof stress test values may not be obtained in less than 30 days of standing at room temperature.

L155 ( solution heat treated and artificially aged ) -Heat for not less than 16 hours at 505-515°C, quench in water at a temperature of 50-70°C, or in a polymer quenchant not hotter than 30°C. Artificially age by heating at 130-150°C for not less than 16 hours. 

Applications

This alloy is commonly used in aircraft but it can also be used in general engineering and transport, e.g., fly wheel housings, rear axle housings, bus wheels, aircraft wheels, fittings, crank cases. L154 and L155 have slightly better foundry characteristics than some previously used L Series alloys. Excellent mechanical properties make them particularly suitable for highly stressed castings and, when the alloy is solution heat treated, for components requiring maximum resistance to shock.