AZ91B (AZ91B-F, M11912) Magnesium
AZ91B magnesium is a magnesium alloy. Cited properties are appropriate for the as-fabricated (no temper or treatment) condition. AZ91B is the ASTM designation for this material. M11912 is the UNS number.
It has a moderately low electrical conductivity and a moderately low melting temperature among magnesium alloys.
The graph bars on the material properties cards below compare AZ91B 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
63
Compressive (Crushing) Strength
160 MPa 23 x 103 psi
Elastic (Young's, Tensile) Modulus
46 GPa 6.7 x 106 psi
Elongation at Break
5.0 %
Fatigue Strength
79 MPa 11 x 103 psi
Poisson's Ratio
0.29
Rockwell F Hardness
75
Shear Modulus
18 GPa 2.6 x 106 psi
Shear Strength
140 MPa 20 x 103 psi
Tensile Strength: Ultimate (UTS)
240 MPa 35 x 103 psi
Tensile Strength: Yield (Proof)
160 MPa 23 x 103 psi
Thermal Properties
Latent Heat of Fusion
360 J/g
Maximum Temperature: Mechanical
130 °C 270 °F
Melting Completion (Liquidus)
600 °C 1100 °F
Melting Onset (Solidus)
470 °C 880 °F
Specific Heat Capacity
990 J/kg-K 0.24 BTU/lb-°F
Thermal Conductivity
73 W/m-K 42 BTU/h-ft-°F
Thermal Expansion
26 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
11 % IACS
Electrical Conductivity: Equal Weight (Specific)
58 % IACS
Otherwise Unclassified Properties
Base Metal Price
12 % relative
Density
1.7 g/cm3 110 lb/ft3
Embodied Carbon
22 kg CO2/kg material
Embodied Energy
160 MJ/kg 67 x 103 BTU/lb
Embodied Water
990 L/kg 120 gal/lb
Common Calculations
Resilience: Ultimate (Unit Rupture Work)
11 MJ/m3
Resilience: Unit (Modulus of Resilience)
280 kJ/m3
Stiffness to Weight: Axial
15 points
Stiffness to Weight: Bending
69 points
Strength to Weight: Axial
38 points
Strength to Weight: Bending
49 points
Thermal Diffusivity
42 mm2/s
Thermal Shock Resistance
14 points
Alloy Composition
| Mg | 87.9 to 91.2 | |
| Al | 8.3 to 9.7 | |
| Zn | 0.35 to 1.0 | |
| Mn | 0.13 to 0.5 | |
| Si | 0 to 0.5 | |
| Cu | 0 to 0.35 | |
| Ni | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM B94: Standard Specification for Magnesium-Alloy Die 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