Plastic Nylon vs. Stainless Steel 303

Compare Plastic Nylon vs. Stainless Steel 303 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	63.1MPasourcetypical	275MPasourceOutokumpu typical (product P = hot rolled plate, transverse)
Ultimate tensile strength	63.1MPasourcetypical, peak stress (= stress at yield)	585MPasourceOutokumpu typical
Flexural strength	82.9MPasourcetypical	not sourced
Elongation at break	not sourced	35%sourceOutokumpu typical, A5
Young's modulus (stiffness)	2.33GPasourcetypical	200GPasourceat RT (Table 12)
Density	1,140kg/m³sourcetypical	7,900kg/m³sourceat RT
Strength to weight	55.4kN·m/kg1.59x higher	34.8kN·m/kg
Stiffness to weight	2.04MN·m/kg	25.3MN·m/kg12.4x higher
Poisson's ratio	0.4sourcebase material: unfilled polyamide (PA), conditioned, maker design-guide family value (Covestro Table 3-1)	0.3sourcedesign value (structural stainless steels)
Shear modulus	0.833GPa	76.9GPa92.4x stiffer in shear
Bulk modulus	3.89GPa	167GPa
Speed of sound	1,430m/s	5,032m/s
Thermal
Thermal conductivity	0.33W/m·Ksourcebase material: unreinforced BASF Ultramid PA66 (A3K) and PA6 (B3S), 23 C (same value for both)	15W/m·Ksourceat RT
Thermal expansion	98–102µm/m·Ksourcebase material: unreinforced BASF Ultramid PA66 (A3K, 98) and PA6 (B3S, 102), 23-55 C	16µm/m·Ksourcemean, 20–100 °C
100 mm part over a 50 °C swing	500µm growth	80µm growth6.25x less
Specific heat	1,700J/kg·Ksourcebase material: unreinforced BASF Ultramid PA66 (A3K) and PA6 (B3S), 23 C (same value for both)	500J/kg·Ksourceat RT
Heats up and cools (diffusivity)	0.17mm²/s	3.8mm²/s22.3x faster
Thermal shock resistance	53.6W/m	902W/m16.8x more resistant
Melting point	188°Csourcetypical	not sourced
Glass transition	55.1°Csourcetypical	not sourced
Max service temperature	89.2°CsourceHDT 0.455 MPa (printed specimens)	871°Csourcecontinuous, scaling limit
Values for	Ultimaker Nylon, 3D-printed specimens, XY (flat), conditioned >=24 h at room temperature; 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 v2.00, April 20, 2022.	1.4305 / UNS S30300, Outokumpu typical values (hot rolled, solution annealed) from 'Steel Grades, Properties and Global Standards'; max service from Carpenter CarTech 303 datasheet

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

Questions

Is Plastic Nylon stronger than Stainless Steel 303?

Stainless Steel 303 is stronger: its yield strength is 275 MPa against 63.1 MPa for Plastic Nylon (4.36x).

Which is lighter, Plastic Nylon or Stainless Steel 303?

Plastic Nylon is lighter: 1,140 kg/m³ against 7,900 kg/m³ for Stainless Steel 303.

Which is stiffer, Plastic Nylon or Stainless Steel 303?

Stainless Steel 303 is stiffer: Young's modulus 200 GPa against 2.33 GPa for Plastic Nylon, so the same part in Stainless Steel 303 deflects less under the same load.

Which is lighter for the same job, Plastic Nylon or Stainless Steel 303?

For the same stiffness or strength: Plastic Nylon is lighter for a stiff panel or plate, strong rod or tie, strong beam, strong panel or plate; Stainless Steel 303 is lighter for a stiff rod or tie (tension), stiff beam (bending).

Part that must be	Plastic Nylon	Stainless Steel 303
Stiff rod or tie (tension)	12.4x heavier	lighter
Stiff beam (bending)	34% heavier	lighter
Stiff panel or plate	lighter	1.57x heavier
Strong rod or tie	lighter	1.59x heavier
Strong beam	lighter	2.6x heavier
Strong panel or plate	lighter	3.32x 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 Nylon or Stainless Steel 303?

Stainless Steel 303 conducts heat better: 15 W/m·K against 0.33 W/m·K for Plastic Nylon.

Which expands less with temperature?

Stainless Steel 303 expands less: 16 µm/m·K against 100 µm/m·K for Plastic Nylon.

Among 59 materials

Stiffness against density

Strength against density