# AZ91B (AZ91B-F, M11912) Magnesium

AZ91B magnesium is a magnesium alloy. It is typically furnished in 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 melting temperature relative to other magnesium alloys in the database. The graph bars on the material properties cards below compare AZ91B magnesium to other magnesium alloys (top) and the entire database (bottom).

## 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

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*

## 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 *m ^{2}/s*

Thermal Shock Resistance

14 *points*

## Alloy Composition

Mg | 87.8 to 91.6 | |

Al | 8.0 to 10 | |

Zn | 0.3 to 1.0 | |

Mn | 0.1 to 0.6 | |

Si | 0 to 0.5 | |

Cu | 0 to 0.35 | |

Ni | 0 to 0.030 | |

Fe | 0 to 0.030 | |

res. | 0 to 0.050 |

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

ISO 16220: Magnesium and magnesium alloys - Magnesium alloy ingots and 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.