Magnesium EQ-21A-T6 Alloy (UNS M18330 )

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations


Magnesium alloys are lightweight materials that are in great demand in the aerospace industry. Today the scope for application has widened. Magnesium alloys contain one of these elements aluminium - zinc, manganese, silicon, copper, rare earths and zirconium, in combination with magnesium.

Magnesium EQ-21A-T6 alloy is similar to magnesium QE22A; however it possesses less silver, thereby lowering the cost. This is a cast alloy with excellent short-time elevated-temperature mechanical properties, pressure tightness, and weldability.

The following datasheet gives an overview of magnesium EQ-21A-T6 alloy.

Chemical Composition

The following table shows the chemical composition of magnesium EQ-21A-T6 alloy.

Element Content (%)
Magnesium, Mg 95.7
Neodymium, Nd 1.5 - 3
Silver, Ag 1.3 - 1.7
Zirconium, Zr 0.40 - 1
Copper, Cu 0.050 - 0.10
Nickel, Ni ≤ 0.010
Other, total ≤ 0.30

Physical Properties

The physical properties of magnesium EQ-21A-T6 alloy are given in the following table.

Properties Metric Imperial
Density 1.81 g/cm³ 0.0654 lb/in³
Melting point 540 - 640°C 1000 - 1180°F

Mechanical Properties

The mechanical properties of magnesium EQ-21A-T6 alloy are outlined in the following table.

Properties Metric Imperial
Tensile strength 234 MPa 234 psi
Yield strength (@strain 0.200 %) 193 MPa 28000 psi
Elastic modulus 45 GPa 6530 ksi
Shear modulus 17 GPa 2470 ksi
Poisson's ratio 0.35 0.35
Elongation at break (in 50mm) 2% 2.00%
Hardness, Brinell 65-85 65-85

Thermal Properties

The thermal properties of magnesium EQ-21A-T6 alloy are highlighted in the following table.

Properties Metric Imperial
Thermal expansion co-efficient (@0.000-100°C/ 32-212°F) 26.7 µm/m°C 14.8 µin/in°F
Thermal conductivity 113 W/mK 784 BTU in/hr.ft².°F

Other Designations

Equivalent materials to magnesium EQ-21A-T6 alloy are listed below:

  • EN 1753 MC65220
  • AMS 4417
  • ASTM B 80
  • ASTM B 199
  • ASTM B 403


Magnesium EQ-21A-T6 alloy is chiefly used for industry and military sand and permanent-mold castings used in solution-treated and artificially aged condition (T6-temper) with high yield strengths.

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