Stainless 17-4PH vs. Steel AISI 1045

Compare Stainless 17-4PH vs. Steel AISI 1045 strength, stiffness, weight and thermal properties.

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Mechanical
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Yield strength	1,275MPasourcetypical, transverse, sheet/strip	531MPasourceproducer-stated, cold drawn
Ultimate tensile strength	1,379MPasourcetypical, transverse, sheet/strip	627MPasourceproducer-stated, cold drawn
Elongation at break	9%sourcetypical, transverse, in 2 in. (50.8 mm)	12%sourcein 2 in (50.8 mm)
Young's modulus (stiffness)	197GPasourceH 900	210GPasourcetypical
Density	7,800kg/m³sourceH 900	7,800kg/m³sourcetypical
Strength to weight	163kN·m/kg2.4x higher	68.1kN·m/kg
Stiffness to weight	25.3MN·m/kg	26.9MN·m/kg7% higher
Poisson's ratio	0.272sourceH 900 (column)	0.3sourcetypical
Shear modulus	77.4GPa	80.8GPa4% stiffer in shear
Bulk modulus	144GPa	175GPa
Speed of sound	5,026m/s	5,189m/s
Thermal
Thermal conductivity	17.9W/m·Ksourceat 149 °C (300 °F), H 900	40–45W/m·Ksourcetypical range, ambient
Thermal expansion	10.8µm/m·Ksourcemean, 21–93 °C (70–200 °F), H 900	12µm/m·Ksourcetypical, mean 20-300 °C
100 mm part over a 50 °C swing	54µm growth11% less	60µm growth
Specific heat	460J/kg·Ksourcemean, 0–100 °C, H 900	460–480J/kg·Ksourcetypical range, 50/100 °C
Heats up and cools (diffusivity)	4.99mm²/s	11.6mm²/s2.32x faster
Thermal shock resistance	7,809W/m25% more resistant	6,269W/m
Max service temperature	316°Csourcestrength-retention limit (not oxidation)	not sourced
Values for	Cleveland-Cliffs 17-4 PH, Condition H 900, sheet/strip, transverse (Product Data Bulletin, May 2021)	AISI 1045 cold drawn bar (Niagara LaSalle) for mechanical; Ovako C45 (lists 'SAE 1045' as a similar designation) for physical constants

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 Stainless 17-4PH stronger than Steel AISI 1045?

Stainless 17-4PH is stronger: its yield strength is 1,275 MPa against 531 MPa for Steel AISI 1045 (2.4x).

Which is lighter, Stainless 17-4PH or Steel AISI 1045?

Stainless 17-4PH is lighter: 7,800 kg/m³ against 7,800 kg/m³ for Steel AISI 1045.

Which is stiffer, Stainless 17-4PH or Steel AISI 1045?

Steel AISI 1045 is stiffer: Young's modulus 210 GPa against 197 GPa for Stainless 17-4PH, so the same part in Steel AISI 1045 deflects less under the same load.

Which is lighter for the same job, Stainless 17-4PH or Steel AISI 1045?

For the same stiffness or strength: Stainless 17-4PH is lighter for a strong rod or tie, strong beam, strong panel or plate; Steel AISI 1045 is lighter for a stiff rod or tie (tension), stiff beam (bending), stiff panel or plate.

Part that must be	Stainless 17-4PH	Steel AISI 1045
Stiff rod or tie (tension)	7% heavier	lighter
Stiff beam (bending)	3% heavier	lighter
Stiff panel or plate	2% heavier	lighter
Strong rod or tie	lighter	2.4x heavier
Strong beam	lighter	1.79x heavier
Strong panel or plate	lighter	1.55x 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, Stainless 17-4PH or Steel AISI 1045?

Steel AISI 1045 conducts heat better: 42.5 W/m·K against 17.9 W/m·K for Stainless 17-4PH.

Which expands less with temperature?

Stainless 17-4PH expands less: 10.8 µm/m·K against 12 µm/m·K for Steel AISI 1045.

Among 59 materials

Stiffness against density

Strength against density