Jul 31 2013
Topics Covered
Introduction
Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations
Applications
Introduction
Magnesium is the eighth most abundant element in the Earth's crust by mass. It is principally obtained by the electrolysis of fused magnesium chloride from sea water, wells and brines. Magnesium HM21A-T81 alloy developed for use at elevated temperatures. It is commonly available in sheet and plate forms.
The following datasheet gives an overview of magnesium HM21A-T81 alloy.
Chemical Composition
The following table shows the chemical composition of magnesium HM21A-T81 alloy.
Element |
Content (%) |
Magnesium, Mg |
97 |
Thorium, Th |
1.5 - 2.5 |
Manganese, Mn |
0.45 - 1.1 |
Physical Properties
The physical properties of magnesium HM21A-T81 alloy are given in the following table.
Properties |
Metric |
Imperial |
Density |
1.78 g/cm³ |
0.0643 lb/in³ |
Mechanical Properties
The mechanical properties of magnesium HM21A-T81 alloy are listed in the following table.
Properties |
Metric |
Imperial |
Tensile strength |
255 MPa |
37000 psi |
Yield strength |
210 MPa |
30500 psi |
Compressive yield strength |
180 MPa |
26100 psi |
Ultimate bearing strength |
455 MPa |
66000 psi |
Bearing yield strength |
320 MPa |
46400 psi |
Shear strength |
170 MPa |
24700 psi |
Shear modulus |
17 GPa |
2470 ksi |
Elastic modulus |
45 GPa |
6530 ksi |
Poisson's ratio |
0.35 |
0.35 |
Elongation at break (in 50 mm) |
6% |
6% |
Machinability (relative rating, 100=best) |
100 |
100 |
Thermal Properties
The following table outlines the thermal properties of magnesium HM21A-T81 alloy.
Properties |
Metric |
Imperial |
Thermal expansion co-efficient (at 0-100°C/32-212°F) |
26.8 µm/m°C |
14.9 µin/in°F |
Thermal conductivity |
135 W/mK |
937 BTU in/hr.ft².°F |
Other Designations
An equivalent material to magnesium HM21A-T81 alloy is AMS 4383.
Applications
Magnesium HM21A-T81 alloy is used in a number of missile and satellite programs, including Polaris, Agena and Titan.