DMLS 17-4PH Stainless Steel vs. Magnesium AZ91D

Compare DMLS 17-4PH Stainless Steel vs. Magnesium AZ91D strength, stiffness, weight and thermal properties.

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DMLS 17-4PH Stainless Steel3D printed metal (DMLS)

Mechanical
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Yield strength	861MPasourcemean, as built, horizontal (N=72)	150MPasourcetypical, 0.2% tensile yield, ambient temperature
Ultimate tensile strength	886MPasourcemean, as built, horizontal (N=72)	230MPasourcetypical, ambient temperature
Elongation at break	19.9%sourcemean at break, as built, horizontal	3%sourcetypical, ambient temperature
Young's modulus (stiffness)	197GPasourcebase material: wrought 17-4 PH, Condition H 900 (Cleveland-Cliffs)	45GPasourcetypical
Density	7,790kg/m³sourcemean part density (ISO 3369)	1,810kg/m³sourcetypical
Strength to weight	110kN·m/kg33% higher	82.9kN·m/kg
Stiffness to weight	25.3MN·m/kg2% higher	24.9MN·m/kg
Poisson's ratio	0.272sourcebase material: wrought 17-4 PH, all conditions (Cleveland-Cliffs)	0.35sourcebase material: AZ91C casting (MIL-HDBK-5J handbook physical constant)
Shear modulus	77.4GPa4.65x stiffer in shear	16.7GPa
Bulk modulus	144GPa	50GPa
Speed of sound	5,029m/s	4,986m/s
Thermal
Thermal conductivity	17.9W/m·Ksourcebase material: wrought 17-4 PH, Condition H 900, at 149 °C (Cleveland-Cliffs)	72W/m·Ksourcetypical
Thermal expansion	10.4µm/m·Ksourcemean 25-100 °C, ASTM E228, AFTER atmospheric heat treatment (as-built value not published)	25µm/m·Ksourcetypical, temperature range not stated
100 mm part over a 50 °C swing	52µm growth2.4x less	125µm growth
Specific heat	460J/kg·Ksourcebase material: wrought 17-4 PH, Condition A, 0-100 °C (Cleveland-Cliffs)	1,050J/kg·Ksourcetypical
Heats up and cools (diffusivity)	5mm²/s	37.9mm²/s7.58x faster
Thermal shock resistance	5,474W/m	6,240W/m14% more resistant
Melting point	not sourced	470–595°Csourcemelting range
Values for	EOS StainlessSteel 17-4PH IndustryLine (powder 9011-0041), EOS M 290, 40 µm, default job 17-4PH_040_StainlessM291_100, as built, horizontal; ISO 6892 & ASTM E8M	ELEKTRON AZ91D magnesium die-casting alloy, as cast; Magnesium Elektron datasheet 475 (7/01), typical properties; Poisson from MIL-HDBK-5J for AZ91C castings.

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.

DMLS 17-4PH Stainless Steel is 3D printed: its properties depend on build direction and print settings; these are typical values.

Questions

Is DMLS 17-4PH Stainless Steel stronger than Magnesium AZ91D?

DMLS 17-4PH Stainless Steel is stronger: its yield strength is 861 MPa against 150 MPa for Magnesium AZ91D (5.74x).

Which is lighter, DMLS 17-4PH Stainless Steel or Magnesium AZ91D?

Magnesium AZ91D is lighter: 1,810 kg/m³ against 7,790 kg/m³ for DMLS 17-4PH Stainless Steel.

Which is stiffer, DMLS 17-4PH Stainless Steel or Magnesium AZ91D?

DMLS 17-4PH Stainless Steel is stiffer: Young's modulus 197 GPa against 45 GPa for Magnesium AZ91D, so the same part in DMLS 17-4PH Stainless Steel deflects less under the same load.

Which is lighter for the same job, DMLS 17-4PH Stainless Steel or Magnesium AZ91D?

For the same stiffness or strength: DMLS 17-4PH Stainless Steel is lighter for a stiff rod or tie (tension), strong rod or tie; Magnesium AZ91D is lighter for a stiff beam (bending), stiff panel or plate, strong beam, strong panel or plate.

Part that must be	DMLS 17-4PH Stainless Steel	Magnesium AZ91D
Stiff rod or tie (tension)	lighter	2% heavier
Stiff beam (bending)	2.06x heavier	lighter
Stiff panel or plate	2.63x heavier	lighter
Strong rod or tie	lighter	33% heavier
Strong beam	34% heavier	lighter
Strong panel or plate	1.8x 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).

Which conducts heat better, DMLS 17-4PH Stainless Steel or Magnesium AZ91D?

Magnesium AZ91D conducts heat better: 72 W/m·K against 17.9 W/m·K for DMLS 17-4PH Stainless Steel.

Which expands less with temperature?

DMLS 17-4PH Stainless Steel expands less: 10.4 µm/m·K against 25 µm/m·K for Magnesium AZ91D.

Among 72 materials

Stiffness against density

Strength against density