Magnesium HM21A-T81 Alloy (UNS M16600)

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.

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