EQ21A (EQ21A-T6, M18330) Magnesium
EQ21A magnesium is a magnesium alloy. Cited properties are appropriate for the T6 temper. To achieve this temper, the metal is solution heat-treated and artificially aged until it meets standard mechanical property requirements. EQ21A is the ASTM designation for this material. M18330 is the UNS number.
It has a very high base cost among magnesium alloys. In addition, it has a moderately high density and a fairly high embodied energy.
The graph bars on the material properties cards below compare EQ21A magnesium to other magnesium alloys (top) and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.
Mechanical Properties
Brinell Hardness
80
Compressive (Crushing) Strength
350 MPa 50 x 103 psi
Elastic (Young's, Tensile) Modulus
44 GPa 6.3 x 106 psi
Elongation at Break
2.4 %
Fatigue Strength
110 MPa 15 x 103 psi
Fracture Toughness
16 MPa-m1/2 15 x 103 psi-in1/2
Poisson's Ratio
0.29
Shear Modulus
17 GPa 2.5 x 106 psi
Shear Strength
150 MPa 22 x 103 psi
Tensile Strength: Ultimate (UTS)
250 MPa 37 x 103 psi
Tensile Strength: Yield (Proof)
190 MPa 28 x 103 psi
Thermal Properties
Latent Heat of Fusion
340 J/g
Maximum Temperature: Mechanical
160 °C 320 °F
Melting Completion (Liquidus)
640 °C 1180 °F
Melting Onset (Solidus)
560 °C 1040 °F
Solidification (Pattern Maker's) Shrinkage
1.3 %
Specific Heat Capacity
980 J/kg-K 0.23 BTU/lb-°F
Thermal Conductivity
110 W/m-K 65 BTU/h-ft-°F
Thermal Expansion
27 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
25 % IACS
Electrical Conductivity: Equal Weight (Specific)
120 % IACS
Otherwise Unclassified Properties
Base Metal Price
80 % relative
Density
1.9 g/cm3 120 lb/ft3
Embodied Carbon
27 kg CO2/kg material
Embodied Energy
210 MJ/kg 89 x 103 BTU/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
5.6 MJ/m3
Resilience: Unit (Modulus of Resilience)
410 kJ/m3
Stiffness to Weight: Axial
13 points
Stiffness to Weight: Bending
63 points
Strength to Weight: Axial
37 points
Strength to Weight: Bending
47 points
Thermal Diffusivity
62 mm2/s
Thermal Shock Resistance
15 points
Alloy Composition
| Mg | 93.9 to 96.8 | |
| Ag | 1.3 to 1.7 | |
| Zr | 0.4 to 1.0 | |
| Cu | 0.050 to 0.1 | |
| Ni | 0 to 0.010 | |
| rare e. | 1.5 to 3.0 | |
| res. | 0 to 0.3 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
Magnesium Alloys Containing Rare Earth Metals: Structure and Properties, L.L. Rokhlin, 2003
ASTM B199: Standard Specification for Magnesium-Alloy Permanent Mold Castings
ASTM B403: Standard Specification for Magnesium-Alloy Investment Castings
ASTM B80: Standard Specification for Magnesium-Alloy Sand Castings
Essential Readings in Magnesium Technology, Suveen N. Mathaudhu et al. (editors), 2014
Environmental Degradation of Advanced and Traditional Engineering Materials, Lloyd H. Hihara et al., 2014.
Advanced Materials in Automotive Engineering, Jason Rowe (editor), 2012
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015