SLS PA12 Nylon vs. Steel AISI 4340

Compare SLS PA12 Nylon vs. Steel AISI 4340 strength, stiffness, weight and thermal properties.

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Mechanical
Try it on a partA bracket to run stress or thermal on, free in your browser	Open in LessCAD	Open in LessCAD
Yield strength	not given (tensile used)	1,035MPasourcetypical, transverse
Ultimate tensile strength	48MPasourcetypical	1,140MPasourcetypical, transverse
Elongation at break	18%sourcetypical	18%sourcetypical, transverse
Young's modulus (stiffness)	1.65GPasourcetypical	200GPasourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered)
Density	930kg/m³sourcetypical8.43x lighter	7,840kg/m³sourcetypical
Strength to weight	51.6kN·m/kg	132kN·m/kg2.56x higher
Stiffness to weight	1.77MN·m/kg	25.5MN·m/kg14.4x higher
Poisson's ratio	not sourced	0.32sourceMIL-HDBK-5J design value (AISI 4340, quenched and tempered)
Shear modulus	not sourced	75.7GPa
Bulk modulus	not sourced	185GPa
Speed of sound	1,332m/s	5,049m/s
Thermal
Thermal conductivity	not sourced	37.5W/m·Ksourcetypical
Thermal expansion	not sourced	11.3µm/m·Ksourcemean, -18 to 93 °C
100 mm part over a 50 °C swing	not sourced	56.5µm growth
Specific heat	not sourced	448J/kg·Ksourcetypical
Heats up and cools (diffusivity)	not sourced	10.7mm²/s
Thermal shock resistance	not sourced	11,678W/m
Melting point	176°Csourcetypical	not sourced
Max service temperature	64°CsourceHDT 1.8 MPa, X orientation	not sourced
Values for	EOS PA 2200 (PA12) Material Data Sheet, process parameter 'Balance' at 120 µm layer thickness, X orientation, dry (conditioned values not given). Live MDS status 04.10.2026, last changed 10.09.2026; PDF via ?topdf=... link on the same page.	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.

SLS PA12 Nylon is 3D printed: its properties depend on build direction and print settings; these are typical values.

Questions

Is SLS PA12 Nylon stronger than Steel AISI 4340?

Steel AISI 4340 is stronger: its yield strength is 1,035 MPa against tensile strength 48 MPa for SLS PA12 Nylon (21.6x).

Which is lighter, SLS PA12 Nylon or Steel AISI 4340?

SLS PA12 Nylon is lighter: 930 kg/m³ against 7,840 kg/m³ for Steel AISI 4340.

Which is stiffer, SLS PA12 Nylon or Steel AISI 4340?

Steel AISI 4340 is stiffer: Young's modulus 200 GPa against 1.65 GPa for SLS PA12 Nylon, so the same part in Steel AISI 4340 deflects less under the same load.

Which is lighter for the same job, SLS PA12 Nylon or Steel AISI 4340?

For the same stiffness or strength: SLS PA12 Nylon is lighter for a stiff panel or plate, strong beam, strong panel or plate; Steel AISI 4340 is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie.

Part that must be	SLS PA12 Nylon	Steel AISI 4340
Stiff rod or tie (tension)	14.4x heavier	lighter
Stiff beam (bending)	31% heavier	lighter
Stiff panel or plate	lighter	1.7x heavier
Strong rod or tie	2.56x heavier	lighter
Strong beam	lighter	9% heavier
Strong panel or plate	lighter	1.82x 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).

Among 59 materials

Stiffness against density

Strength against density