Thermal conductivity against densityHigher and further left: spreads more heat for its weightThermal expansion against thermal conductivityLower and further right: warps less when heated
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Sources4 documents: Outokumpu, Cleveland-Cliffs, Steel Construction Institute, Carpenter Technology
Stainless Steel 303
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
Stainless Steel 304
Type 304, annealed flat-rolled (Cleveland-Cliffs 304/304L Product Data Bulletin, May 2021); Poisson's ratio from the Nickel Institute/SCI structural stainless design manual
1
Steel Grades, Properties and Global StandardsOutokumpuarchived copyStainless Steel 303 · Yield strength: Outokumpu typical (product P = hot rolled plate, transverse)Stainless Steel 303 · Ultimate tensile strength: Outokumpu typicalStainless Steel 303 · Elongation at break: Outokumpu typical, A5Stainless Steel 303 · Young's modulus (stiffness): at RT (Table 12)Stainless Steel 303 · Density: at RTStainless Steel 303 · Thermal conductivity: at RTStainless Steel 303 · Thermal expansion: mean, 20–100 °CStainless Steel 303 · Specific heat: at RT
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304/304L Stainless Steel Product Data Bulletin (2021)Cleveland-CliffsStainless Steel 304 · Yield strength: typical, annealed, 70 °F (21 °C)Stainless Steel 304 · Ultimate tensile strength: typical, annealed, 70 °F (21 °C)Stainless Steel 304 · Elongation at break: typical, annealed, in 2 in. (50.8 mm)Stainless Steel 304 · Young's modulus (stiffness): typical, in tensionStainless Steel 304 · Density: typicalStainless Steel 304 · Thermal conductivity: at 100 °CStainless Steel 304 · Thermal expansion: mean, 0–100 °CStainless Steel 304 · Specific heat: mean, 0–100 °CStainless Steel 304 · Melting point: melting rangeStainless Steel 304 · Max service temperature: continuous, oxidation (scaling) limit in air
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Design Manual for Structural Stainless Steel, 4th Edition (P413)Steel Construction Institutearchived copyStainless Steel 303 · Poisson's ratio: design value (structural stainless steels)Stainless Steel 304 · Poisson's ratio: design value (structural stainless steels)
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Carpenter Stainless Type 303 Data SheetCarpenter Technologyarchived copyStainless Steel 303 · Max service temperature: continuous, scaling limit
Each number points to the document that states it, with the exact basis. Values without a number are computed from the sourced ones. "Not sourced" means no citable source states it (or only a specification minimum); figures computed from it are left out too.
Questions
Mechanical
Is Stainless Steel 303 stronger than Stainless Steel 304?
Stainless Steel 303 is stronger: its yield strength is 275 MPa against 241 MPa for Stainless Steel 304 (14%).
Which is lighter, Stainless Steel 303 or Stainless Steel 304?
Stainless Steel 303 is lighter: 7,900 kg/m³ against 8,030 kg/m³ for Stainless Steel 304.
Which is stiffer, Stainless Steel 303 or Stainless Steel 304?
Stainless Steel 303 is stiffer: Young's modulus 200 GPa against 193 GPa for Stainless Steel 304, so the same part in Stainless Steel 303 deflects less under the same load.
Which is lighter for the same job, Stainless Steel 303 or Stainless Steel 304?
For the same stiffness or strength: Stainless Steel 303 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate, strong rod or tie, strong beam, strong panel or plate.
Part that must be
Stainless Steel 303
Stainless Steel 304
Stiff rod or tie (tension)
lighter
5% heavier
Stiff beam (bending)
lighter
3% heavier
Stiff panel or plate
lighter
3% heavier
Strong rod or tie
lighter
16% heavier
Strong beam
lighter
11% heavier
Strong panel or plate
lighter
9% 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 is more ductile, Stainless Steel 303 or Stainless Steel 304?
Stainless Steel 304 stretches further before it breaks: 55% elongation at break against 35% for Stainless Steel 303.
Thermal
Which conducts heat better, Stainless Steel 303 or Stainless Steel 304?
Stainless Steel 304 conducts heat better: 16.2 W/m·K against 15 W/m·K for Stainless Steel 303.
Which expands less with temperature?
Stainless Steel 303 expands less: 16 µm/m·K against 16.9 µm/m·K for Stainless Steel 304.