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Magnesium AZ91D vs. Steel AISI 4340 Compare Magnesium AZ91D vs. Steel AISI 4340 strength, stiffness, weight and thermal properties.
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Plastic PLA Plastic PETG Plastic ABS Plastic TPU Plastic Nylon Plastic ABS (bulk/injection) Plastic Polycarbonate Plastic POM/Acetal Plastic Nylon PA6 Plastic Nylon PA66 Plastic PEEK Plastic PTFE Plastic UHMWPE Plastic HDPE Plastic Polypropylene Plastic PMMA Plastic PBT GF30 Plastic PPS GF40 Plastic LCP GF30 Rubber Wood Aluminum Aluminum 6061-T6 Aluminum 7075-T6 Aluminum 2024-T351 Aluminum 5052-H32 Aluminum 7050-T7451 Aluminum A380 Aluminum 6063-T6 Aluminum 1100-O Aluminum ADC12 Steel Steel AISI 1018 Steel AISI 1045 Steel AISI 4340 Steel A992 Iron Titanium Titanium Ti-6Al-4V Stainless Steel 304 Stainless Steel 316 Stainless Steel 303 Stainless Steel 17-4PH Brass C360 Brass C260 Copper C110 Glass Nickel Inconel 718 Magnesium AZ31B-H24 Magnesium AZ91D Zinc Zamak 3 FDM ASA FDM Polycarbonate FDM PAHT-CF FDM HIPS SLA Resin Standard SLA Resin Tough 2000 SLA Resin Elastic 50A SLS PA12 Nylon DMLS AlSi10Mg Aluminum DMLS Ti-6Al-4V ELI Titanium DMLS 316L Stainless Steel DMLS 17-4PH Stainless Steel Concrete Brick Plywood Drywall PCB Laminate FR-4 Silicon Ceramic Alumina 96% Ceramic Aluminum Nitride Solder SAC305 Magnesium AZ91D Cast Plastic PLA Plastic PETG Plastic ABS Plastic TPU Plastic Nylon Plastic ABS (bulk/injection) Plastic Polycarbonate Plastic POM/Acetal Plastic Nylon PA6 Plastic Nylon PA66 Plastic PEEK Plastic PTFE Plastic UHMWPE Plastic HDPE Plastic Polypropylene Plastic PMMA Plastic PBT GF30 Plastic PPS GF40 Plastic LCP GF30 Rubber Wood Aluminum Aluminum 6061-T6 Aluminum 7075-T6 Aluminum 2024-T351 Aluminum 5052-H32 Aluminum 7050-T7451 Aluminum A380 Aluminum 6063-T6 Aluminum 1100-O Aluminum ADC12 Steel Steel AISI 1018 Steel AISI 1045 Steel AISI 4340 Steel A992 Iron Titanium Titanium Ti-6Al-4V Stainless Steel 304 Stainless Steel 316 Stainless Steel 303 Stainless Steel 17-4PH Brass C360 Brass C260 Copper C110 Glass Nickel Inconel 718 Magnesium AZ31B-H24 Magnesium AZ91D Zinc Zamak 3 FDM ASA FDM Polycarbonate FDM PAHT-CF FDM HIPS SLA Resin Standard SLA Resin Tough 2000 SLA Resin Elastic 50A SLS PA12 Nylon DMLS AlSi10Mg Aluminum DMLS Ti-6Al-4V ELI Titanium DMLS 316L Stainless Steel DMLS 17-4PH Stainless Steel Concrete Brick Plywood Drywall PCB Laminate FR-4 Silicon Ceramic Alumina 96% Ceramic Aluminum Nitride Solder SAC305 Steel AISI 4340 Wrought Try it on a partA bracket to run stress or thermal on, free in your browser Open in LessCAD Open in LessCAD Mechanical Yield strength 150 MPa source typical, 0.2% tensile yield, ambient temperature 1,035 MPa source typical, transverse Ultimate tensile strength 230 MPa source typical, ambient temperature 1,140 MPa source typical, transverse Elongation at break 3 % source typical, ambient temperature 18 % source typical, transverse Young's modulus (stiffness) 45 GPa source typical 200 GPa source MIL-HDBK-5J design value (AISI 4340, quenched and tempered) Density 1,810 kg/m³ source typical 4.33x lighter 7,840 kg/m³ source typical Strength to weight 82.9 kN·m/kg 132 kN·m/kg 1.59x higher Stiffness to weight 24.9 MN·m/kg 25.5 MN·m/kg 3% higher Poisson's ratio 0.35 source base material: AZ91C casting (MIL-HDBK-5J handbook physical constant) 0.32 source MIL-HDBK-5J design value (AISI 4340, quenched and tempered) Shear modulus 16.7 GPa 75.7 GPa 4.54x stiffer in shear Bulk modulus 50 GPa 185 GPa Speed of sound 4,986 m/s 5,049 m/s Thermal Thermal conductivity 72 W/m·K source typical 1.92x more heat through a fin 37.5 W/m·K source typical Thermal expansion 25 µm/m·K source typical, temperature range not stated 11.3 µm/m·K source mean, -18 to 93 °C 100 mm part over a 50 °C swing 125 µm growth 56.5 µm growth 2.21x less Specific heat 1,050 J/kg·K source typical 448 J/kg·K source typical Heats up and cools (diffusivity) 37.9 mm²/s 3.55x faster 10.7 mm²/s Thermal shock resistance 6,240 W/m 11,678 W/m 1.87x more resistant Melting point 470–595 °C source melting range not sourced 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. Carpenter (Latrobe) Lescalloy 4340 VAC-ARC datasheet; mechanical row for 1100 °F temper; physical properties grade-level
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 Steel AISI 4340? Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against 150 MPa for Magnesium AZ91D (6.9x).
Which is lighter, Magnesium AZ91D or Steel AISI 4340? Magnesium AZ91D is lighter: 1,810 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.
Which is stiffer, Magnesium AZ91D or Steel AISI 4340? Steel AISI 4340 is stiffer: Young's modulus 200 GPa against 45 GPa for Magnesium AZ91D, so the same part in Steel AISI 4340 deflects less under the same load.
Which is lighter for the same job, Magnesium AZ91D or Steel AISI 4340? For the same stiffness or strength: Magnesium AZ91D is lighter for a stiff beam (bending), stiff panel or plate, strong beam, strong panel or plate; Steel AISI 4340 is lighter for a stiff rod or tie (tension), strong rod or tie.
Part that must be Magnesium AZ91D Steel AISI 4340 Stiff rod or tie (tension) 3% heavier lighter Stiff beam (bending) lighter 2.06x heavier Stiff panel or plate lighter 2.63x heavier Strong rod or tie 1.59x heavier lighter Strong beam lighter 20% heavier Strong panel or plate lighter 1.65x 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 Steel AISI 4340? Magnesium AZ91D conducts heat better: 72 W/m·K against 37.5 W/m·K for Steel AISI 4340.
Which expands less with temperature? Steel AISI 4340 expands less: 11.3 µm/m·K against 25 µm/m·K for Magnesium AZ91D.
Among 72 materials 1k 10k 0.1 1 10 100 Density (kg/m³) Young's modulus (GPa) Plastic PLA Plastic PETG Plastic ABS Plastic TPU Plastic Nylon Aluminum Steel Iron Titanium Steel AISI 1018 Stainless Steel 304 Stainless Steel 316 Aluminum 6061-T6 Aluminum 7075-T6 Brass C360 Copper C110 Glass Steel AISI 1045 Steel A992 Stainless Steel 303 Stainless Steel 17-4PH Aluminum 2024-T351 Aluminum 5052-H32 Aluminum 7050-T7451 Titanium Ti-6Al-4V Brass C260 Nickel Inconel 718 Magnesium AZ31B-H24 Zinc Zamak 3 Plastic ABS (bulk/injection) Plastic Polycarbonate Plastic POM/Acetal Plastic Nylon PA6 Plastic Nylon PA66 Plastic PEEK Plastic UHMWPE Plastic HDPE Plastic Polypropylene Plastic PMMA FDM ASA FDM Polycarbonate FDM PAHT-CF FDM HIPS SLA Resin Tough 2000 SLS PA12 Nylon DMLS AlSi10Mg Aluminum DMLS Ti-6Al-4V ELI Titanium DMLS 316L Stainless Steel DMLS 17-4PH Stainless Steel PCB Laminate FR-4 Silicon Ceramic Alumina 96% Ceramic Aluminum Nitride Aluminum A380 Aluminum 6063-T6 Aluminum 1100-O Aluminum ADC12 Solder SAC305 Plastic PBT GF30 Plastic PPS GF40 Plastic LCP GF30 Magnesium AZ91D Steel AISI 4340 Stiffness against density 1k 10k 10 100 1k Density (kg/m³) Yield strength (MPa) Plastic PLA Plastic PETG Plastic ABS Plastic TPU Plastic Nylon Rubber Aluminum Steel Iron Titanium Steel AISI 1018 Stainless Steel 304 Stainless Steel 316 Aluminum 6061-T6 Aluminum 7075-T6 Brass C360 Copper C110 Glass Steel AISI 1045 Steel A992 Stainless Steel 303 Stainless Steel 17-4PH Aluminum 2024-T351 Aluminum 5052-H32 Aluminum 7050-T7451 Titanium Ti-6Al-4V Brass C260 Nickel Inconel 718 Magnesium AZ31B-H24 Zinc Zamak 3 Plastic ABS (bulk/injection) Plastic Polycarbonate Plastic POM/Acetal Plastic Nylon PA6 Plastic Nylon PA66 Plastic PEEK Plastic PTFE Plastic UHMWPE Plastic HDPE Plastic Polypropylene Plastic PMMA FDM ASA FDM Polycarbonate FDM PAHT-CF FDM HIPS SLA Resin Tough 2000 SLA Resin Elastic 50A SLS PA12 Nylon DMLS AlSi10Mg Aluminum DMLS Ti-6Al-4V ELI Titanium DMLS 316L Stainless Steel DMLS 17-4PH Stainless Steel Brick PCB Laminate FR-4 Silicon Ceramic Alumina 96% Aluminum A380 Aluminum 6063-T6 Aluminum 1100-O Aluminum ADC12 Solder SAC305 Plastic PBT GF30 Plastic PPS GF40 Plastic LCP GF30 Magnesium AZ91D Steel AISI 4340 Strength against density