Magnesium AZ31B-O (UNS M11311) Alloy

Topics Covered

Chemical Composition
Physical Properties
Mechanical Properties
Thermal Properties
Other Designations


Magnesium AZ31B-O alloy is available in the form of annealed sheets. This datasheet will elaborate on the properties and applications of this alloy.

Chemical Composition

The following table provides the chemical composition of magnesium AZ31B-O alloy.

Element Content (%)
Magnesium, Mg 97
Aluminum, Al 2.5-3.5
Zinc, Zn 0.60-1.4
Manganese, Mn ≥0.20
Silicon, Si ≤0.10
Copper, Cu ≤0.050
Calcium, Ca ≤0.040
Iron, Fe ≤0.0050
Nickel, Ni ≤0.0050

Physical Properties

The physical properties of magnesium AZ31B-O alloy are given in the following table.

Properties Metric Imperial
Density 1.77 g/cc 0.0639 lb/in³
Melting Point 605-630°C 1120-1170°F

Mechanical Properties

The mechanical properties of magnesium AZ31B-O alloy are listed in the table below.

Properties Metric Imperial
Tensile Strength 255 MPa 37000 psi
Yield strength (@strain 0.200%) 150 MPa 21800 psi
Compressive Yield Strength (at 0.2% offset) 110 MPa 16000 psi
Ultimate Bearing Strength 485 MPa 70300 psi
Bearing Yield Strength 290 MPa 42100 psi
Elongation at break (in 50 mm) 21% 21%
Elastic Modulus (in tension) 45 GPa 6530 ksi
Poisson's ratio 0.35 0.35
Shear Modulus 17 GPa 2470 ksi
Shear Strength 145 MPa 21000 psi
Machinability (relative rating, 100=Best) 100 100
Hardness, Brinell (500 kg load, 10 mm ball) 56 56
Hardness, Knoop (estimated from Brinell) 71 71
Hardness, Vickers (estimated from Brinell) 83 83

Thermal Properties

The following table outlines the thermal properties of magnesium AZ31B-O alloy.

Properties Metric Imperial
Thermal expansion co-efficient (@ 0.000-100°C/32-212°F) 26 µm/m°C 14.4 µin/in°F
Thermal Conductivity 96 W/mK 666 BTU in/hr.ft².°F

Other Designations

Some of the other designations that are used to denote magnesium AZ31B-O alloy are:-

  • UNS M11210


Magnesium AZ31B-O alloy is used in aircraft fuselage, cell phones and camera cases, textile machinery and concrete tools.

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