Cleveland-Cliffs / AK Steel ARMCO Pure Iron Product Data Bulletin (07/2022): Table 1 typical physical properties, Table 2 typical mechanical properties after SRA/recrystallization anneal.
Zamak 3 (ASTM B86 die cast), Nathan Trotter (zinc alloy producer) technical data sheet, typical values
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 Iron stronger than Zinc Zamak 3?
Zinc Zamak 3 is stronger: its yield strength is 221 MPa against 186 MPa for Iron (19%).
Which is lighter, Iron or Zinc Zamak 3?
Zinc Zamak 3 is lighter: 6,600 kg/m³ against 7,860 kg/m³ for Iron.
Which is stiffer, Iron or Zinc Zamak 3?
Iron is stiffer: Young's modulus 207 GPa against 85.5 GPa for Zinc Zamak 3, so the same part in Iron deflects less under the same load.
Which is lighter for the same job, Iron or Zinc Zamak 3?
For the same stiffness or strength: Iron is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate; Zinc Zamak 3 is lighter for a strong rod or tie, strong beam, strong panel or plate.
Part that must be
Iron
Zinc Zamak 3
Stiff rod or tie (tension)
lighter
2.03x heavier
Stiff beam (bending)
lighter
31% heavier
Stiff panel or plate
lighter
13% heavier
Strong rod or tie
42% heavier
lighter
Strong beam
34% heavier
lighter
Strong panel or plate
30% heavier
lighter
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, Iron or Zinc Zamak 3?
Zinc Zamak 3 conducts heat better: 113 W/m·K against 73.2 W/m·K for Iron.
Which expands less with temperature?
Iron expands less: 13.7 µm/m·K against 27.4 µm/m·K for Zinc Zamak 3.