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Magnesium AZ91D vs. Plastic ABS (bulk/injection)

Compare Magnesium AZ91D vs. Plastic ABS (bulk/injection) strength, stiffness, weight and thermal properties.

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Magnesium AZ91DCast
Plastic ABS (bulk/injection)Bulk polymer (molded or machined)
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Mechanical
Yield strength150MPasourcetypical, 0.2% tensile yield, ambient temperature45MPasourcetypical, tensile stress at yield 23 °C
Ultimate tensile strength230MPasourcetypical, ambient temperaturenot sourced
Flexural strengthnot sourced65MPasourcetypical, 23 °C
Elongation at break3%sourcetypical, ambient temperature10%sourcenominal strain at break, 23 °C
Young's modulus (stiffness)45GPasourcetypical19.6x stiffer2.3GPasourcetypical
Density1,810kg/m³sourcetypical1,040kg/m³sourcetypical1.74x lighter
Strength to weight82.9kN·m/kg1.92x higher43.3kN·m/kg
Stiffness to weight24.9MN·m/kg11.2x higher2.21MN·m/kg
Poisson's ratio0.35sourcebase material: AZ91C casting (MIL-HDBK-5J handbook physical constant)0.39sourcetypical, ABS family (Covestro Part and Mold Design guide, Table 3-1)
Shear modulus16.7GPa20.1x stiffer in shear0.827GPa
Bulk modulus50GPa3.48GPa
Speed of sound4,986m/s1,487m/s
Thermal
Thermal conductivity72W/m·Ksourcetypical424x more heat through a fin0.17W/m·Ksourcetypical
Thermal expansion25µm/m·Ksourcetypical, temperature range not stated80–110µm/m·Ksourcerange
100 mm part over a 50 °C swing125µm growth3.8x less475µm growth
Specific heat1,050J/kg·Ksourcetypicalnot sourced
Heats up and cools (diffusivity)37.9mm²/snot sourced
Thermal shock resistance6,240W/m292x more resistant21.4W/m
Melting point470–595°Csourcemelting rangenot sourced
Max service temperaturenot sourced94°CsourceHDT 1.8 MPa (annealed 4 h/80 °C)
Values forELEKTRON AZ91D magnesium die-casting alloy, as cast; Magnesium Elektron datasheet 475 (7/01), typical properties; Poisson from MIL-HDBK-5J for AZ91C castings.INEOS Styrolution Terluran GP-22 general-purpose injection-molding ABS, ISO typical values (TDS revision 08/01/2022)

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.

Questions

Is Magnesium AZ91D stronger than Plastic ABS (bulk/injection)?

Magnesium AZ91D is stronger: its yield strength is 150 MPa against 45 MPa for Plastic ABS (bulk/injection) (3.33x).

Which is lighter, Magnesium AZ91D or Plastic ABS (bulk/injection)?

Plastic ABS (bulk/injection) is lighter: 1,040 kg/m³ against 1,810 kg/m³ for Magnesium AZ91D.

Which is stiffer, Magnesium AZ91D or Plastic ABS (bulk/injection)?

Magnesium AZ91D is stiffer: Young's modulus 45 GPa against 2.3 GPa for Plastic ABS (bulk/injection), so the same part in Magnesium AZ91D deflects less under the same load.

Which is lighter for the same job, Magnesium AZ91D or Plastic ABS (bulk/injection)?

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, strong panel or plate.

Part that must beMagnesium AZ91DPlastic ABS (bulk/injection)
Stiff rod or tie (tension)lighter11.2x heavier
Stiff beam (bending)lighter2.54x heavier
Stiff panel or platelighter1.55x heavier
Strong rod or tielighter1.92x heavier
Strong beamlighter28% heavier
Strong panel or platelighter5% heavier

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).

Which conducts heat better, Magnesium AZ91D or Plastic ABS (bulk/injection)?

Magnesium AZ91D conducts heat better: 72 W/m·K against 0.17 W/m·K for Plastic ABS (bulk/injection).

Which expands less with temperature?

Magnesium AZ91D expands less: 25 µm/m·K against 95 µm/m·K for Plastic ABS (bulk/injection).

Among 72 materials

1k10k0.1110100Density (kg/m³)Young's modulus (GPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel AISI 4340Steel A992Stainless Steel 303Stainless Steel 17-4PHAluminum 2024-T351Aluminum 5052-H32Aluminum 7050-T7451Titanium Ti-6Al-4VBrass C260Nickel Inconel 718Magnesium AZ31B-H24Zinc Zamak 3Plastic PolycarbonatePlastic POM/AcetalPlastic Nylon PA6Plastic Nylon PA66Plastic PEEKPlastic UHMWPEPlastic HDPEPlastic PolypropylenePlastic PMMAFDM ASAFDM PolycarbonateFDM PAHT-CFFDM HIPSSLA Resin Tough 2000SLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelPCB Laminate FR-4SiliconCeramic Alumina 96%Ceramic Aluminum NitrideAluminum A380Aluminum 6063-T6Aluminum 1100-OAluminum ADC12Solder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Magnesium AZ91DPlastic ABS (bulk/injection)
Stiffness against density
1k10k101001kDensity (kg/m³)Yield strength (MPa)Plastic PLAPlastic PETGPlastic ABSPlastic TPUPlastic NylonRubberAluminumSteelIronTitaniumSteel AISI 1018Stainless Steel 304Stainless Steel 316Aluminum 6061-T6Aluminum 7075-T6Brass C360Copper C110GlassSteel AISI 1045Steel AISI 4340Steel A992Stainless Steel 303Stainless Steel 17-4PHAluminum 2024-T351Aluminum 5052-H32Aluminum 7050-T7451Titanium Ti-6Al-4VBrass C260Nickel Inconel 718Magnesium AZ31B-H24Zinc Zamak 3Plastic PolycarbonatePlastic POM/AcetalPlastic Nylon PA6Plastic Nylon PA66Plastic PEEKPlastic PTFEPlastic UHMWPEPlastic HDPEPlastic PolypropylenePlastic PMMAFDM ASAFDM PolycarbonateFDM PAHT-CFFDM HIPSSLA Resin Tough 2000SLA Resin Elastic 50ASLS PA12 NylonDMLS AlSi10Mg AluminumDMLS Ti-6Al-4V ELI TitaniumDMLS 316L Stainless SteelDMLS 17-4PH Stainless SteelBrickPCB Laminate FR-4SiliconCeramic Alumina 96%Aluminum A380Aluminum 6063-T6Aluminum 1100-OAluminum ADC12Solder SAC305Plastic PBT GF30Plastic PPS GF40Plastic LCP GF30Magnesium AZ91DPlastic ABS (bulk/injection)
Strength against density

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