UNS S17700 (17-7 PH, Alloy 631) Stainless Steel
S17700 stainless steel is a precipitation-hardening stainless steel formulated for primary forming into wrought products. S17700 is the UNS number for this material. 17-7 PH is the common industry name.
It can have the lowest ductility among the wrought precipitation-hardening stainless steels in the database.
The properties of S17700 stainless steel include four 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 S17700 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
180 to 430
Elastic (Young's, Tensile) Modulus
200 GPa 28 x 106 psi
Elongation at Break
1.0 to 23 %
Fatigue Strength
290 to 560 MPa 42 to 81 x 103 psi
Poisson's Ratio
0.28
Rockwell C Hardness
41 to 46
Shear Modulus
76 GPa 11 x 106 psi
Shear Strength
740 to 940 MPa 110 to 140 x 103 psi
Tensile Strength: Ultimate (UTS)
1180 to 1650 MPa 170 to 240 x 103 psi
Tensile Strength: Yield (Proof)
430 to 1210 MPa 62 to 180 x 103 psi
Thermal Properties
Latent Heat of Fusion
290 J/g
Maximum Temperature: Corrosion
410 °C 770 °F
Maximum Temperature: Mechanical
890 °C 1640 °F
Melting Completion (Liquidus)
1440 °C 2620 °F
Melting Onset (Solidus)
1400 °C 2550 °F
Specific Heat Capacity
480 J/kg-K 0.12 BTU/lb-°F
Thermal Conductivity
15 W/m-K 8.9 BTU/h-ft-°F
Thermal Expansion
11 µm/m-K
Electrical Properties
Electrical Conductivity: Equal Volume
2.3 % IACS
Electrical Conductivity: Equal Weight (Specific)
2.7 % IACS
Otherwise Unclassified Properties
Base Metal Price
13 % relative
Density
7.7 g/cm3 480 lb/ft3
Embodied Carbon
2.8 kg CO2/kg material
Embodied Energy
40 MJ/kg 17 x 103 BTU/lb
Embodied Water
150 L/kg 17 gal/lb
Common Calculations
PREN (Pitting Resistance)
17
Resilience: Ultimate (Unit Rupture Work)
15 to 210 MJ/m3
Resilience: Unit (Modulus of Resilience)
460 to 3750 kJ/m3
Stiffness to Weight: Axial
14 points
Stiffness to Weight: Bending
25 points
Strength to Weight: Axial
42 to 59 points
Strength to Weight: Bending
32 to 40 points
Thermal Diffusivity
4.1 mm2/s
Thermal Shock Resistance
39 to 54 points
Alloy Composition
Among wrought stainless steels, the composition of S17700 stainless steel is notable for including aluminum (Al). Aluminum is used to improve oxidation resistance. It can also enhance the effects of heat treatment.
| Fe | 70.5 to 76.8 | |
| Cr | 16 to 18 | |
| Ni | 6.5 to 7.8 | |
| Al | 0.75 to 1.5 | |
| Mn | 0 to 1.0 | |
| Si | 0 to 1.0 | |
| C | 0 to 0.090 | |
| P | 0 to 0.040 | |
| S | 0 to 0.030 |
All values are % weight. Ranges represent what is permitted under applicable standards.
Followup Questions
Similar Alloys
Further Reading
ASTM A693: Standard Specification for Precipitation-Hardening Stainless and Heat-Resisting Steel Plate, Sheet, and Strip
ASTM A564: Standard Specification for Hot-Rolled and Cold-Finished Age-Hardening Stainless Steel Bars and Shapes
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
CRC Materials Science and Engineering Handbook, 4th ed., James F. Shackelford et al. (editors), 2015