Plastic PLA vs. Stainless 17-4PH

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

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Mechanical
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Yield strength	52.5MPasourcetypical	1,275MPasourcetypical, transverse, sheet/strip
Ultimate tensile strength	52.5MPasourcetypical, peak stress (= stress at yield)	1,379MPasourcetypical, transverse, sheet/strip
Flexural strength	96.8MPasourcetypical	not sourced
Elongation at break	7.8%sourcetypical	9%sourcetypical, transverse, in 2 in. (50.8 mm)
Young's modulus (stiffness)	3.25GPasourcetypical	197GPasourceH 900
Density	1,240kg/m³sourcetypical	7,800kg/m³sourceH 900
Strength to weight	42.3kN·m/kg	163kN·m/kg3.86x higher
Stiffness to weight	2.62MN·m/kg	25.3MN·m/kg9.64x higher
Poisson's ratio	not sourced	0.272sourceH 900 (column)
Shear modulus	not sourced	77.4GPa
Bulk modulus	not sourced	144GPa
Speed of sound	1,619m/s	5,026m/s
Thermal
Thermal conductivity	0.13W/m·Ksourcebase material: NatureWorks Ingeo biopolymer, amorphous sheet, 25 °C	17.9W/m·Ksourceat 149 °C (300 °F), H 900
Thermal expansion	not sourced	10.8µm/m·Ksourcemean, 21–93 °C (70–200 °F), H 900
100 mm part over a 50 °C swing	not sourced	54µm growth
Specific heat	1,200J/kg·Ksourcebase material: NatureWorks Ingeo biopolymer, amorphous sheet, 25 °C	460J/kg·Ksourcemean, 0–100 °C, H 900
Heats up and cools (diffusivity)	0.0874mm²/s	4.99mm²/s57.1x faster
Thermal shock resistance	not sourced	7,809W/m
Melting point	152°Csourcetypical	not sourced
Glass transition	59.1°Csourcetypical	not sourced
Max service temperature	58.8°CsourceHDT 0.455 MPa (printed specimens)	316°Csourcestrength-retention limit (not oxidation)
Values for	Ultimaker PLA, 3D-printed specimens, XY (flat) orientation; 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 dated April 20, 2022.	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.

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

Questions

Is Plastic PLA stronger than Stainless 17-4PH?

Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 52.5 MPa for Plastic PLA (24.3x).

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

Plastic PLA is lighter: 1,240 kg/m³ against 7,800 kg/m³ for Stainless 17-4PH.

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

Stainless 17-4PH is stiffer: Young's modulus 197 GPa against 3.25 GPa for Plastic PLA, so the same part in Stainless 17-4PH deflects less under the same load.

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

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

Part that must be	Plastic PLA	Stainless 17-4PH
Stiff rod or tie (tension)	9.64x heavier	lighter
Stiff beam (bending)	24% heavier	lighter
Stiff panel or plate	lighter	1.6x heavier
Strong rod or tie	3.86x heavier	lighter
Strong beam	33% heavier	lighter
Strong panel or plate	lighter	28% 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 PLA or Stainless 17-4PH?

Stainless 17-4PH conducts heat better: 17.9 W/m·K against 0.13 W/m·K for Plastic PLA.

Among 59 materials

Stiffness against density

Strength against density