# 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 10 ^{3} psi*

Elastic (Young's, Tensile) Modulus

46 *GPa* 6.7 *x 10 ^{6} psi*

Elongation at Break

5.0 *%*

Fatigue Strength

79 *MPa* 11 *x 10 ^{3} psi*

Poisson's Ratio

0.29

Rockwell F Hardness

75

Shear Modulus

18 *GPa* 2.6 *x 10 ^{6} psi*

Shear Strength

140 *MPa* 20 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

240 *MPa* 35 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

160 *MPa* 23 *x 10 ^{3} 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/cm ^{3}* 110

*lb/ft*

^{3}Embodied Carbon

22 *kg CO _{2}/kg material*

Embodied Energy

160 *MJ/kg* 67 *x 10 ^{3} BTU/lb*

Embodied Water

990 *L/kg* 120 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

11 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

280 *kJ/m ^{3}*

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 *mm ^{2}/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