Elektron® 21 Sand Casting Ingot

Luxfer MEL Technologies has developed this lightweight, high performance alloy for aerospace applications. It is designed to provide superior mechanical properties and improved corrosion resistance together with good castability.

• AMS 4429
• UNS M12310
• MMPDS
• ASTM B80
• ISO 16220 MC65410

• Zinc: 0.2–0.5%
• Neodymium: 2.6–3.1%
• Gadolinium: 1.0–1.7%
• Zirconium: Saturated
• Magnesium: Balance

Castings are given the following T6 heat treatment to obtain optimum mechanical properties.

Solution treat for 8 hours at 520˚C (970˚F), Hot water quench using water at 60–80˚C (140–175˚F) or polymer quench, Age for 16 hours at 200˚C (400˚F), Air cool.

• Specific gravity: 1.82
• Coefficient of thermal expansion: 26.3 x 10-6K-1
• Thermal conductivity: 116 Wm-1K-1
• Specific heat: 1,086 Jkg-1K-1
• Electrical resistivity: 94.6 nΩm
• Modulus of elasticity: 44.8 x 103 MPa
• Poissons ratio: 0.27
• Melting range: 545–640˚C
• Brinell hardness: 65–75

Minimum specification tensile properties.

• 0.2% proof stress: 145 MPa
• Elongation: 2%

Castability

• Excellent castability as a consequence of low oxidation characteristics.
• Fine-grained microstructure.
• Pressure tight.

Pattern Makers Shrinkage Factor

1.5%

Weldability

Weldable by the tungsten arc inert gas process (TIG) with a filler rod of a similar composition. Castings should be heat treated after welding to obtain optimum properties.

Machining

Elektron® 21 castings, like all magnesium alloy castings, machine faster than any other metal. Providing the geometry of the part allows, the limiting factor is the power and speed of the machine rather than the quality of the tool material. The power required per cubic centimetre of metal removed varies from 9 to 14 watts per minute depending on the operation.

Surface Treatment

All the normal chromating, anodising and finishing treatments are applicable.

Corrosion Resistance

ASTM B117 salt spray test corrosion rate for base metal:

• <1.14 mg/cm2/day
• <90 mpy

Typical tensile properties

• 0.2% proof stress: 170 MPa
• Tensile strength: 280 MPa
• Elongation: 5%

Typical compressive properties

• 0.2% proof stress: 168 MPa
• Ultimate strength: 367 MPa

Typical shear properties

Ultimate stress: 172 MPa

Fracture toughness

KIC: 15.5 MPa m1/2

Fatigue properties

• Pull-pull fatigue: R = 0.1
• 5 x 107 cycles
• 115–120 MPa

Low temperature mechanical properties

Typical mechanical properties at -35˚C

• Elongation: 7%
• Ultimate tensile strength: 270 MPa
• Impact value (notched): 1.7 J

Elevated Temperature Mechanical Properties

Typical Tensile Properties

Figure 1. Effect of temperature on tensile properties.

Creep Properties

Figure 2. Stress /time relationship at 200˚C (0.1% creep strain).

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