Ultimaker PETG, 3D-printed specimens, XY (flat); 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 v1.00, April 29, 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 PETG is 3D printed: its properties depend on build direction and print settings; these are typical values.
Questions
Is Plastic PETG stronger than Stainless Steel 303?
Stainless Steel 303 is stronger: its yield strength is 275 MPa against 46.2 MPa for Plastic PETG (5.95x).
Which is lighter, Plastic PETG or Stainless Steel 303?
Plastic PETG is lighter: 1,270 kg/m³ against 7,900 kg/m³ for Stainless Steel 303.
Which is stiffer, Plastic PETG or Stainless Steel 303?
Stainless Steel 303 is stiffer: Young's modulus 200 GPa against 1.94 GPa for Plastic PETG, so the same part in Stainless Steel 303 deflects less under the same load.
Which is lighter for the same job, Plastic PETG or Stainless Steel 303?
For the same stiffness or strength: Plastic PETG 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 PETG
Stainless Steel 303
Stiff rod or tie (tension)
16.6x heavier
lighter
Stiff beam (bending)
1.63x heavier
lighter
Stiff panel or plate
lighter
33% heavier
Strong rod or tie
lighter
5% heavier
Strong beam
lighter
1.89x heavier
Strong panel or plate
lighter
2.55x 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 PETG or Stainless Steel 303?
Stainless Steel 303 conducts heat better: 15 W/m·K against 0.21 W/m·K for Plastic PETG.
Which expands less with temperature?
Stainless Steel 303 expands less: 16 µm/m·K against 51 µm/m·K for Plastic PETG.