Plastic Nylon PA66 vs. Stainless 17-4PH

Compare Plastic Nylon PA66 vs. Stainless 17-4PH strength, stiffness, weight and thermal properties.

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Plastic Nylon PA66Bulk polymer (molded or machined)

Mechanical
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Yield strength	85MPasourcetypical, dry	1,275MPasourcetypical, transverse, sheet/strip
Ultimate tensile strength	not sourced	1,379MPasourcetypical, transverse, sheet/strip
Elongation at break	30%sourcenominal strain at break, dry	9%sourcetypical, transverse, in 2 in. (50.8 mm)
Young's modulus (stiffness)	3GPasourcetypical, dry	197GPasourceH 900
Density	1,130kg/m³sourcetypical	7,800kg/m³sourceH 900
Strength to weight	75.2kN·m/kg	163kN·m/kg2.17x higher
Stiffness to weight	2.65MN·m/kg	25.3MN·m/kg9.51x higher
Poisson's ratio	0.4sourcebase material: unfilled polyamide (PA), conditioned, maker design-guide family value (Covestro Table 3-1)	0.272sourceH 900 (column)
Shear modulus	1.07GPa	77.4GPa72.3x stiffer in shear
Bulk modulus	5GPa	144GPa
Speed of sound	1,629m/s	5,026m/s
Thermal
Thermal conductivity	0.33W/m·Ksourcetypical	17.9W/m·Ksourceat 149 °C (300 °F), H 900
Thermal expansion	98µm/m·Ksourcelongitudinal, 23-55 °C	10.8µm/m·Ksourcemean, 21–93 °C (70–200 °F), H 900
100 mm part over a 50 °C swing	490µm growth	54µm growth9.07x less
Specific heat	1,700J/kg·Ksourcetypical	460J/kg·Ksourcemean, 0–100 °C, H 900
Heats up and cools (diffusivity)	0.172mm²/s	4.99mm²/s29x faster
Thermal shock resistance	57.2W/m	7,809W/m136x more resistant
Melting point	260°CsourceDSC	not sourced
Max service temperature	101°CsourceIEC 60216 temperature index, 20000 h	316°Csourcestrength-retention limit (not oxidation)
Values for	BASF Ultramid A3K (PA66, unreinforced injection-moulding grade), Product Information 02/2026, dry values (ISO methods)	Cleveland-Cliffs 17-4 PH, Condition H 900, sheet/strip, transverse (Product Data Bulletin, May 2021)

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.

Questions

Is Plastic Nylon PA66 stronger than Stainless 17-4PH?

Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 85 MPa for Plastic Nylon PA66 (15x).

Which is lighter, Plastic Nylon PA66 or Stainless 17-4PH?

Plastic Nylon PA66 is lighter: 1,130 kg/m³ against 7,800 kg/m³ for Stainless 17-4PH.

Which is stiffer, Plastic Nylon PA66 or Stainless 17-4PH?

Stainless 17-4PH is stiffer: Young's modulus 197 GPa against 3 GPa for Plastic Nylon PA66, so the same part in Stainless 17-4PH deflects less under the same load.

Which is lighter for the same job, Plastic Nylon PA66 or Stainless 17-4PH?

For the same stiffness or strength: Plastic Nylon PA66 is lighter for a stiff panel or plate, strong beam, strong panel or plate; Stainless 17-4PH is lighter for a stiff rod or tie (tension), stiff beam (bending), strong rod or tie.

Part that must be	Plastic Nylon PA66	Stainless 17-4PH
Stiff rod or tie (tension)	9.51x heavier	lighter
Stiff beam (bending)	17% heavier	lighter
Stiff panel or plate	lighter	1.71x heavier
Strong rod or tie	2.17x heavier	lighter
Strong beam	lighter	13% heavier
Strong panel or plate	lighter	1.78x 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 PA66 or Stainless 17-4PH?

Stainless 17-4PH conducts heat better: 17.9 W/m·K against 0.33 W/m·K for Plastic Nylon PA66.

Which expands less with temperature?

Stainless 17-4PH expands less: 10.8 µm/m·K against 98 µm/m·K for Plastic Nylon PA66.

Among 59 materials

Stiffness against density

Strength against density