Magnesium AZ91D vs. SLS PA12 Nylon

Compare Magnesium AZ91D vs. SLS PA12 Nylon strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	150MPasourcetypical, 0.2% tensile yield, ambient temperature	not given (tensile used)
Ultimate tensile strength	230MPasourcetypical, ambient temperature	48MPasourcetypical
Elongation at break	3%sourcetypical, ambient temperature	18%sourcetypical
Young's modulus (stiffness)	45GPasourcetypical27.3x stiffer	1.65GPasourcetypical
Density	1,810kg/m³sourcetypical	930kg/m³sourcetypical1.95x lighter
Strength to weight	82.9kN·m/kg1.61x higher	51.6kN·m/kg
Stiffness to weight	24.9MN·m/kg14x higher	1.77MN·m/kg
Poisson's ratio	0.35sourcebase material: AZ91C casting (MIL-HDBK-5J handbook physical constant)	not sourced
Shear modulus	16.7GPa	not sourced
Bulk modulus	50GPa	not sourced
Speed of sound	4,986m/s	1,332m/s
Thermal
Thermal conductivity	72W/m·Ksourcetypical	not sourced
Thermal expansion	25µm/m·Ksourcetypical, temperature range not stated	not sourced
100 mm part over a 50 °C swing	125µm growth	not sourced
Specific heat	1,050J/kg·Ksourcetypical	not sourced
Heats up and cools (diffusivity)	37.9mm²/s	not sourced
Thermal shock resistance	6,240W/m	not sourced
Melting point	470–595°Csourcemelting range	176°Csourcetypical
Max service temperature	not sourced	64°CsourceHDT 1.8 MPa, X orientation
Values for	ELEKTRON AZ91D magnesium die-casting alloy, as cast; Magnesium Elektron datasheet 475 (7/01), typical properties; Poisson from MIL-HDBK-5J for AZ91C castings.	EOS PA 2200 (PA12) Material Data Sheet, process parameter 'Balance' at 120 µm layer thickness, X orientation, dry (conditioned values not given). Live MDS status 04.10.2026, last changed 10.09.2026; PDF via ?topdf=... link on the same page.

Every value links to the document that states it. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.

SLS PA12 Nylon is 3D printed: its properties depend on build direction and print settings; these are typical values.

Questions

Is Magnesium AZ91D stronger than SLS PA12 Nylon?

Magnesium AZ91D is stronger: its yield strength is 150 MPa against tensile strength 48 MPa for SLS PA12 Nylon (3.13x).

Which is lighter, Magnesium AZ91D or SLS PA12 Nylon?

SLS PA12 Nylon is lighter: 930 kg/m³ against 1,810 kg/m³ for Magnesium AZ91D.

Which is stiffer, Magnesium AZ91D or SLS PA12 Nylon?

Magnesium AZ91D is stiffer: Young's modulus 45 GPa against 1.65 GPa for SLS PA12 Nylon, so the same part in Magnesium AZ91D deflects less under the same load.

Which is lighter for the same job, Magnesium AZ91D or SLS PA12 Nylon?

For the same stiffness or strength: Magnesium AZ91D is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam; SLS PA12 Nylon is lighter for a strong panel or plate.

Part that must be	Magnesium AZ91D	SLS PA12 Nylon
Stiff rod or tie (tension)	lighter	14x heavier
Stiff beam (bending)	lighter	2.68x heavier
Stiff panel or plate	lighter	1.55x heavier
Strong rod or tie	lighter	1.61x heavier
Strong beam	lighter	10% heavier
Strong panel or plate	10% heavier	lighter

For the same stiffness or strength, mass scales with density over stiffness (or strength) raised to a power set by how the part is loaded: 1 for a rod in tension, 1/2 for a beam in bending, 1/3 for a panel (the standard material-selection indices).

Among 72 materials

Stiffness against density

Strength against density