For use at temperatures up to 200˚C, this alloy has excellent corrosion resistance characteristics and castability, making it the suitable material for a range of aerospace applications.
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
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.
Figure 2. Stress /time relationship at 200˚C (0.1% creep strain).
