Plastic Polycarbonate vs. DMLS 316L Stainless Steel

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

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Plastic PolycarbonateBulk polymer (molded or machined)

DMLS 316L Stainless Steel3D printed metal (DMLS)

Mechanical
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Yield strength	65MPasourcetypical, tensile yield	530MPasourcetypical, as manufactured, horizontal
Ultimate tensile strength	65MPasourcetypical, stress at break	640MPasourcetypical, as manufactured, horizontal
Flexural strength	97MPasourcetypical, flexural strength	not sourced
Elongation at break	125%sourcetypical, strain at break	40%sourcetypical at break, as manufactured, horizontal
Young's modulus (stiffness)	2.4GPasourcetypical	185GPasourcetypical, as built, horizontal (XY); EOSINT M280-400W / M290-400W, 316L_Surface 1.0, 20 µm (2014 sheet)
Density	1,200kg/m³sourcetypical	7,900kg/m³sourcepart density (ISO 3369, not labelled min or typical), EOS M 290, 40 µm FlexLine
Strength to weight	54.2kN·m/kg	67.1kN·m/kg24% higher
Stiffness to weight	2MN·m/kg	23.4MN·m/kg11.7x higher
Poisson's ratio	0.38sourcetypical, polycarbonate family (Covestro Part and Mold Design guide, Table 3-1)	0.3sourcebase material: austenitic stainless steels incl. 1.4404 (316L), design value
Shear modulus	0.87GPa	71.2GPa81.8x stiffer in shear
Bulk modulus	3.33GPa	154GPa
Speed of sound	1,414m/s	4,839m/s
Thermal
Thermal conductivity	0.2W/m·Ksourcetypical, through-plane, 23 C	16.2W/m·Ksourcebase material: wrought 316/316L (Cleveland-Cliffs), at 100 °C
Thermal expansion	65µm/m·Ksourcetypical, 23-55 C, parallel and normal	15.7µm/m·Ksourcemean 25-100 °C, ASTM E228
100 mm part over a 50 °C swing	325µm growth	78.6µm growth4.13x less
Specific heat	1,172J/kg·Ksourcetypical (guide value), Bayer ASTM datasheet for Makrolon 2405, ASTM D 2766	500J/kg·Ksourcebase material: wrought 316/316L (Cleveland-Cliffs), 0-100 °C
Heats up and cools (diffusivity)	0.142mm²/s	4.1mm²/s28.8x faster
Thermal shock resistance	51.7W/m	2,067W/m40x more resistant
Glass transition	144°Csourcetypical, DSC 10 C/min	not sourced
Max service temperature	125°CsourceUL 746B RTI, tensile strength, 1.5 mm	not sourced
Values for	Covestro Makrolon 2405 general-purpose PC (MVR 19), Covestro technical datasheet version 2026-09-28, typical values	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.

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

Questions

Is Plastic Polycarbonate stronger than DMLS 316L Stainless Steel?

DMLS 316L Stainless Steel is stronger: its yield strength is 530 MPa against 65 MPa for Plastic Polycarbonate (8.15x).

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

Plastic Polycarbonate is lighter: 1,200 kg/m³ against 7,900 kg/m³ for DMLS 316L Stainless Steel.

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

DMLS 316L Stainless Steel is stiffer: Young's modulus 185 GPa against 2.4 GPa for Plastic Polycarbonate, so the same part in DMLS 316L Stainless Steel deflects less under the same load.

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

For the same stiffness or strength: Plastic Polycarbonate 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 Polycarbonate	DMLS 316L Stainless Steel
Stiff rod or tie (tension)	11.7x heavier	lighter
Stiff beam (bending)	33% heavier	lighter
Stiff panel or plate	lighter	1.55x heavier
Strong rod or tie	24% heavier	lighter
Strong beam	lighter	1.63x heavier
Strong panel or plate	lighter	2.31x 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 Polycarbonate or DMLS 316L Stainless Steel?

DMLS 316L Stainless Steel conducts heat better: 16.2 W/m·K against 0.2 W/m·K for Plastic Polycarbonate.

Which expands less with temperature?

DMLS 316L Stainless Steel expands less: 15.7 µm/m·K against 65 µm/m·K for Plastic Polycarbonate.

Among 59 materials

Stiffness against density

Strength against density