Plastic PETG vs. DMLS 316L Stainless Steel

Compare Plastic PETG vs. DMLS 316L Stainless Steel strength, stiffness, weight and thermal properties.

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DMLS 316L Stainless Steel3D printed metal (DMLS)

Mechanical
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Yield strength	46.2MPasourcetypical	530MPasourcetypical, as manufactured, horizontal
Ultimate tensile strength	46.2MPasourcetypical, peak stress (= stress at yield)	640MPasourcetypical, as manufactured, horizontal
Flexural strength	78.9MPasourcetypical	not sourced
Elongation at break	7.6%sourcetypical	40%sourcetypical at break, as manufactured, horizontal
Young's modulus (stiffness)	1.94GPasourcetypical	185GPasourcetypical, as built, horizontal (XY); EOSINT M280-400W / M290-400W, 316L_Surface 1.0, 20 µm (2014 sheet)
Density	1,270kg/m³sourcetypical	7,900kg/m³sourcepart density (ISO 3369, not labelled min or typical), EOS M 290, 40 µm FlexLine
Strength to weight	36.4kN·m/kg	67.1kN·m/kg1.84x higher
Stiffness to weight	1.53MN·m/kg	23.4MN·m/kg15.3x higher
Poisson's ratio	not sourced	0.3sourcebase material: austenitic stainless steels incl. 1.4404 (316L), design value
Shear modulus	not sourced	71.2GPa
Bulk modulus	not sourced	154GPa
Speed of sound	1,236m/s	4,839m/s
Thermal
Thermal conductivity	0.21W/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical	16.2W/m·Ksourcebase material: wrought 316/316L (Cleveland-Cliffs), at 100 °C
Thermal expansion	51µm/m·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), typical	15.7µm/m·Ksourcemean 25-100 °C, ASTM E228
100 mm part over a 50 °C swing	255µm growth	78.6µm growth3.24x less
Specific heat	1,300J/kg·Ksourcebase material: Eastman Eastar Copolyester 6763 (PETG), DSC at 60 °C (lowest temperature listed)	500J/kg·Ksourcebase material: wrought 316/316L (Cleveland-Cliffs), 0-100 °C
Heats up and cools (diffusivity)	0.127mm²/s	4.1mm²/s32.2x faster
Thermal shock resistance	not sourced	2,067W/m
Glass transition	77.4°Csourcetypical	not sourced
Max service temperature	76.2°CsourceHDT 0.455 MPa (printed specimens)	not sourced
Values for	Ultimaker PETG, 3D-printed specimens, XY (flat); Ultimaker S5 Pro, engineering intent profile, 0.15 mm layer height, AA 0.4 print core, 100% infill, Cura 4.9, printed one-at-a-time, conditioned >=24 h at room temperature. TDS v1.00, April 29, 2022.	EOS StainlessSteel 316L (powder 9011-0032), EOS M 290, ParameterSet 316L 20µm Surface M290/400W, as manufactured, horizontal; ISO 6892-1

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.

Plastic PETG and DMLS 316L Stainless Steel are 3D printed: their properties depend on build direction and print settings; these are typical values.

Questions

Is Plastic PETG stronger than DMLS 316L Stainless Steel?

DMLS 316L Stainless Steel is stronger: its yield strength is 530 MPa against 46.2 MPa for Plastic PETG (11.5x).

Which is lighter, Plastic PETG or DMLS 316L Stainless Steel?

Plastic PETG is lighter: 1,270 kg/m³ against 7,900 kg/m³ for DMLS 316L Stainless Steel.

Which is stiffer, Plastic PETG or DMLS 316L Stainless Steel?

DMLS 316L Stainless Steel is stiffer: Young's modulus 185 GPa against 1.94 GPa for Plastic PETG, so the same part in DMLS 316L Stainless Steel deflects less under the same load.

Which is lighter for the same job, Plastic PETG or DMLS 316L Stainless Steel?

For the same stiffness or strength: Plastic PETG is lighter for a stiff panel or plate, strong beam, strong panel or plate; DMLS 316L Stainless Steel is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie.

Part that must be	Plastic PETG	DMLS 316L Stainless Steel
Stiff rod or tie (tension)	15.3x heavier	lighter
Stiff beam (bending)	1.57x heavier	lighter
Stiff panel or plate	lighter	36% heavier
Strong rod or tie	1.84x heavier	lighter
Strong beam	lighter	22% heavier
Strong panel or plate	lighter	1.84x 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, Plastic PETG or DMLS 316L Stainless Steel?

DMLS 316L Stainless Steel conducts heat better: 16.2 W/m·K against 0.21 W/m·K for Plastic PETG.

Which expands less with temperature?

DMLS 316L Stainless Steel expands less: 15.7 µm/m·K against 51 µm/m·K for Plastic PETG.

Among 59 materials

Stiffness against density

Strength against density