# AZ91D-T4 Magnesium

AZ91D-T4 magnesium is AZ91D magnesium in the T4 temper. To achieve this temper, the metal is solution heat-treated and naturally aged. It has the highest strength and highest ductility compared to the other variants of AZ91D magnesium.

The graph bars on the material properties cards below compare AZ91D-T4 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

60

Compressive (Crushing) Strength

310 *MPa* 45 *x 10 ^{3} psi*

Elastic (Young's, Tensile) Modulus

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

Elongation at Break

4.5 *%*

Fatigue Strength

85 *MPa* 12 *x 10 ^{3} psi*

Impact Strength: V-Notched Charpy

2.7 *J* 2.0 *ft-lb*

Poisson's Ratio

0.29

Rockwell F Hardness

75

Shear Modulus

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

Shear Strength

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

Tensile Strength: Ultimate (UTS)

220 *MPa* 31 *x 10 ^{3} psi*

Tensile Strength: Yield (Proof)

80 *MPa* 12 *x 10 ^{3} psi*

## Thermal Properties

Latent Heat of Fusion

350 *J/g*

Maximum Temperature: Mechanical

130 *°C* 270 *°F*

Melting Completion (Liquidus)

600 *°C* 1100 *°F*

Melting Onset (Solidus)

490 *°C* 920 *°F*

Specific Heat Capacity

990 *J/kg-K* 0.24 *BTU/lb-°F*

Thermal Conductivity

78 *W/m-K* 45 *BTU/h-ft-°F*

Thermal Expansion

27 *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* 68 *x 10 ^{3} BTU/lb*

Embodied Water

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

## Common Calculations

Resilience: Ultimate (Unit Rupture Work)

7.7 *MJ/m ^{3}*

Resilience: Unit (Modulus of Resilience)

69 *kJ/m ^{3}*

Stiffness to Weight: Axial

15 *points*

Stiffness to Weight: Bending

69 *points*

Strength to Weight: Axial

34 *points*

Strength to Weight: Bending

46 *points*

Thermal Diffusivity

45 *mm ^{2}/s*

Thermal Shock Resistance

13 *points*

## Alloy Composition

Mg | 88.7 to 91.2 | |

Al | 8.3 to 9.7 | |

Zn | 0.35 to 1.0 | |

Mn | 0.15 to 0.5 | |

Si | 0 to 0.1 | |

Cu | 0 to 0.030 | |

Fe | 0 to 0.0050 | |

Ni | 0 to 0.0020 |

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

## Followup Questions

## Further Reading

ASTM B94: Standard Specification for Magnesium-Alloy Die Castings

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