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UNS S17400 (17-4 PH, Alloy 630) Stainless Steel

S17400 stainless steel is a precipitation-hardening stainless steel formulated for primary forming into wrought products. S17400 is the UNS number for this material. 17-4 PH is the common industry name.

It has a moderately low embodied energy and can have a moderately low tensile strength among wrought precipitation-hardening stainless steels.

The properties of S17400 stainless steel include eight common variations. This page shows summary ranges across all of them. For more specific values, follow the links immediately below. The graph bars on the material properties cards further below compare S17400 stainless steel to: wrought precipitation-hardening stainless steels (top), all iron alloys (middle), and the entire database (bottom). A full bar means this is the highest value in the relevant set. A half-full bar means it's 50% of the highest, and so on.

Mechanical Properties

Brinell Hardness

280 to 440

Elastic (Young's, Tensile) Modulus

190 GPa 28 x 106 psi

Elongation at Break

11 to 21 %

Fatigue Strength

380 to 670 MPa 55 to 98 x 103 psi

Impact Strength: V-Notched Charpy

7.6 to 86 J 5.6 to 63 ft-lb

Poisson's Ratio


Reduction in Area

40 to 62 %

Rockwell C Hardness

27 to 43

Shear Modulus

75 GPa 11 x 106 psi

Shear Strength

570 to 830 MPa 82 to 120 x 103 psi

Tensile Strength: Ultimate (UTS)

910 to 1390 MPa 130 to 200 x 103 psi

Tensile Strength: Yield (Proof)

580 to 1250 MPa 84 to 180 x 103 psi

Thermal Properties

Latent Heat of Fusion

280 J/g

Maximum Temperature: Corrosion

450 °C 840 °F

Maximum Temperature: Mechanical

850 °C 1570 °F

Melting Completion (Liquidus)

1440 °C 2620 °F

Melting Onset (Solidus)

1400 °C 2550 °F

Specific Heat Capacity

480 J/kg-K 0.11 BTU/lb-°F

Thermal Conductivity

17 W/m-K 9.7 BTU/h-ft-°F

Thermal Expansion

11 µm/m-K

Electrical Properties

Electrical Conductivity: Equal Volume

2.3 % IACS

Electrical Conductivity: Equal Weight (Specific)

2.6 % IACS

Otherwise Unclassified Properties

Base Metal Price

14 % relative


7.8 g/cm3 490 lb/ft3

Embodied Carbon

2.7 kg CO2/kg material

Embodied Energy

39 MJ/kg 17 x 103 BTU/lb

Embodied Water

130 L/kg 16 gal/lb

Common Calculations

PREN (Pitting Resistance)


Resilience: Ultimate (Unit Rupture Work)

140 to 160 MJ/m3

Resilience: Unit (Modulus of Resilience)

880 to 4060 kJ/m3

Stiffness to Weight: Axial

14 points

Stiffness to Weight: Bending

25 points

Strength to Weight: Axial

32 to 49 points

Strength to Weight: Bending

27 to 35 points

Thermal Diffusivity

4.5 mm2/s

Thermal Shock Resistance

30 to 46 points

Alloy Composition

Among wrought stainless steels, the composition of S17400 stainless steel is notable for including niobium (Nb) and copper (Cu). Niobium is primarily used to improve yield strength, particularly at elevated temperatures. Copper is used to improve resistance to acids, and to improve formability.

Iron (Fe) 70.4 to 78.9
Chromium (Cr) 15 to 17
Nickel (Ni) 3.0 to 5.0
Copper (Cu) 3.0 to 5.0
Manganese (Mn) 0 to 1.0
Silicon (Si) 0 to 1.0
Niobium (Nb) 0.15 to 0.45
Carbon (C) 0 to 0.070
Phosphorus (P) 0 to 0.040
Sulfur (S) 0 to 0.030

All values are % weight. Ranges represent what is permitted under applicable standards.

Followup Questions

Similar Alloys

Further Reading

ASTM A564: Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes

Sintering of Advanced Materials: Fundamentals and Processes, Zhigang Zak Fang (editor), 2010

ASTM A276: Standard Specification for Stainless Steel Bars and Shapes

Welding Metallurgy and Weldability of Stainless Steels, John C. Lippold and Damian J. Kotecki, 2005

ASTM A959: Standard Guide for Specifying Harmonized Standard Grade Compositions for Wrought Stainless Steels

Properties and Selection: Irons, Steels and High Performance Alloys, ASM Handbook vol. 1, ASM International, 1993

Corrosion of Stainless Steels, A. John Sedriks, 1996

ASM Specialty Handbook: Stainless Steels, J. R. Davis (editor), 1994

Advances in Stainless Steels, Baldev Raj et al. (editors), 2010