# AZ31B-O Magnesium

AZ31B-O magnesium is AZ31B magnesium in the annealed condition. It has the lowest strength and highest ductility compared to the other variants of AZ31B magnesium. The graph bars on the material properties cards below compare AZ31B-O 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

56

Elastic (Young's, Tensile) Modulus

45 *GPa* 6.5 *x 10 ^{6} psi*

Elongation at Break

12 *%*

Fatigue Strength

120 *MPa* 18 *x 10 ^{3} psi*

Poisson's Ratio

0.29

Shear Modulus

17 *GPa* 2.5 *x 10 ^{6} psi*

Shear Strength

140 *MPa* 21 *x 10 ^{3} psi*

Tensile Strength: Ultimate (UTS)

240 *MPa* 34 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

120 *MPa* 18 *x 10 ^{3} psi*

## Thermal Properties

Latent Heat of Fusion

350 *J/g*

Maximum Temperature: Mechanical

150 *°C* 300 *°F*

Melting Completion (Liquidus)

600 *°C* 1110 *°F*

Melting Onset (Solidus)

600 *°C* 1120 *°F*

Specific Heat Capacity

990 *J/kg-K* 0.24 *BTU/lb-°F*

Thermal Conductivity

100 *W/m-K* 60 *BTU/h-ft-°F*

Thermal Expansion

26 *µm/m-K*

## Electrical Properties

Electrical Conductivity: Equal Volume

18 *% IACS*

Electrical Conductivity: Equal Weight (Specific)

95 *% IACS*

## Otherwise Unclassified Properties

Base Metal Price

12 *% relative*

Density

1.7 *g/cm ^{3}* 110

*lb/ft*

^{3}Embodied Carbon

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

Embodied Energy

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

Embodied Water

970 *L/kg* 120 *gal/lb*

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

25 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

170 *kJ/m ^{3}*

Stiffness to Weight: Axial

15 *points*

Stiffness to Weight: Bending

70 *points*

Strength to Weight: Axial

39 *points*

Strength to Weight: Bending

50 *points*

Thermal Diffusivity

62 *mm ^{2}/s*

Thermal Shock Resistance

14 *points*

## Alloy Composition

Mg | 93.6 to 97.1 | |

Al | 2.4 to 3.6 | |

Zn | 0.5 to 1.5 | |

Mn | 0.050 to 1.0 | |

Si | 0 to 0.1 | |

Fe | 0 to 0.050 | |

Cu | 0 to 0.050 | |

Ca | 0 to 0.040 | |

Ni | 0 to 0.0050 | |

res. | 0 to 0.3 |

All values are % weight. Ranges represent what is permitted under applicable standards.

## Followup Questions

## Further Reading

ASTM B90: Standard Specification for Magnesium-Alloy Sheet and Plate

Advances in Wrought Magnesium Alloys: Fundamentals of Processing, Properties and Applications, Colleen Bettles and Matthew Barnett (editors), 2012

ASTM B91: Standard Specification for Magnesium-Alloy Forgings

ISO 3116: Magnesium and magnesium alloys - Wrought magnesium alloys

Welding and Joining of Magnesium Alloys, Liming Liu (editor), 2010

Essential Readings in Magnesium Technology, Suveen N. Mathaudhu et al. (editors), 2014

Advanced Materials in Automotive Engineering, Jason Rowe (editor), 2012

Properties and Selection: Nonferrous Alloys and Special-Purpose Materials, ASM Handbook vol. 2, ASM International, 1993