877-412-3651 
Stainless Steel 17-4PH
Stainless Steel 17-4PH (UNS S17400, AISI Type 630) is a martensitic precipitation-hardening stainless steel. It contains about 17% chromium, 4% nickel and 4% copper, with a small niobium addition. A single aging treatment raises its tensile strength to between 135 and 200 ksi (930–1380 MPa), and its general corrosion resistance matches Type 304. It keeps high strength and hardness up to about 600°F (316°C).
17-4PH is delivered solution treated (Condition A), when it machines and welds easily. It’s then hardened at a relatively low temperature of 900-1150°F. That treatment causes only a small, predictable size change, so parts can be finished before hardening. Choosing the aging temperature lets engineers trade peak strength for toughness and stress-corrosion resistance.
It’s used across aerospace, oil and gas, chemical processing, food equipment, marine hardware and nuclear service, for pump and valve shafts, gears, fasteners, fittings and structural parts.
Tech Steel & Materials offers the alloy Stainless Steel 17-4PH in 2 sub-type specifications, each in multiple and customized shapes/forms:
For vacuum-remelted 17-4 made for critical aerospace parts, see our CEVM 17-4 stainless steel page.
Stainless Steel 17-4PH Chemical Composition
| Element | Min (%) | Max (%) |
| Chromium (Cr) | 15.00 | 17.50 |
| Nickel (Ni) | 3.00 | 5.00 |
| Copper (Cu) | 3.00 | 5.00 |
| Niobium + Tantalum (Nb + Ta) | 0.15 | 0.45 |
| Carbon (C) | — | 0.07 |
| Manganese (Mn) | — | 1.00 |
| Silicon (Si) | — | 1.00 |
| Phosphorus (P) | — | 0.040 |
| Sulfur (S) | — | 0.030 |
| Iron (Fe) | Balance | |
Fabrication and Working Instructions
- Hot working: Forge from 2050-2200°F (1121-1204°C) and do not work below about 1850°F (1010°C). Air cool, then solution treat at 1900°F (1038°C) before aging.
- Cold forming: Limited in Condition A because of the martensitic structure. Mild bending and forming are best done on sheet and strip, or on material in the overaged H1150 condition.
- Machining: Machines much like Type 304 in Condition A, and better still in H1150. Rough machine before aging, then finish machine with a small allowance for the contraction that occurs during hardening, about 0.0004-0.0006 in/in.
- Cutting: Abrasive waterjet, bandsaw, shearing and machining are preferred. Plasma cutting is not recommended.
- Welding: Welds more readily than conventional martensitic stainless steels by GTAW, GMAW, SMAW and plasma arc, with no preheat required. Use matching AWS ER630 filler, then solution treat and re-age the weldment for full joint strength.
Physical Properties of Stainless Steel 17-4PH
| Property | Imperial | Metric |
| Density (H900) | 0.282 lb/in3 | 7.81 g/cm3 |
| Melting Range | 2560–2625°F | 1404–1440°C |
| Specific Heat (32–212°F) | 0.11 BTU/lb·°F | 460 J/kg·K |
| Electrical Resistivity (Condition A) | 38.6 µΩ·in | 98 µΩ·cm |
| Thermal Expansion, 70–200°F | 6.0 x 10-6 in/in/°F | 10.8 µm/m·°C |
| Thermal Expansion, 70–600°F | 6.2 x 10-6 in/in/°F | 11.2 µm/m·°C |
| Thermal Expansion, 70–800°F | 6.3 x 10-6 in/in/°F | 11.3 µm/m·°C |
| Thermal Conductivity, 300°F | 124 BTU·in/ft²·h·°F | 17.9 W/m·K |
| Thermal Conductivity, 500°F | 135 BTU·in/ft²·h·°F | 19.5 W/m·K |
| Thermal Conductivity, 900°F | 157 BTU·in/ft²·h·°F | 22.6 W/m·K |
| Modulus of Elasticity (H900) | 28.5 x 103 ksi | 197 GPa |
| Modulus of Rigidity (Torsion) | 9.68 x 103 ksi | 67 GPa |
| Poisson’s Ratio (H900) | 0.272 | 0.272 |
| Magnetic | Ferromagnetic in all conditions | |
Stainless Steel 17-4PH Mechanical Properties
| Condition | Tensile Strength (min) | Yield Strength 0.2% (min) | Elongation (min) | Reduction of Area (min) | Hardness (HRC) |
| H900 | 190 ksi (1310 MPa) | 170 ksi (1170 MPa) | 10% | 40% | 40–47 |
| H925 | 170 ksi (1170 MPa) | 155 ksi (1070 MPa) | 10% | 44% | 38–45 |
| H1025 | 155 ksi (1070 MPa) | 145 ksi (1000 MPa) | 12% | 45% | 34–42 |
| H1075 | 145 ksi (1000 MPa) | 125 ksi (860 MPa) | 13% | 45% | 31–38 |
| H1100 | 140 ksi (965 MPa) | 115 ksi (795 MPa) | 14% | 45% | 30–37 |
| H1150 | 135 ksi (930 MPa) | 105 ksi (725 MPa) | 16% | 50% | 28–37 |
Longitudinal minimums for bar up to 8 in (203 mm) per ASTM A564 / AMS 5643. Typical Charpy V-notch impact energy rises from about 15 ft-lb in H900 to about 50 ft-lb in H1150 and about 100 ft-lb in H1150M.
Heat Treatment
All conditions start from Condition A: solution treated at 1900°F ± 25°F (1038°C) for 30 minutes and cooled below 90°F (32°C). Condition A is not intended for service. The steel is then aged at one of the temperatures below; the condition name is the aging temperature in °F.
| Condition | Aging Temperature (± 15°F) | Time at Temperature, Then Cooling |
| H900 | 900°F (482°C) | 1 hour, air cool |
| H925 | 925°F (496°C) | 4 hours, air cool |
| H1025 | 1025°F (552°C) | 4 hours, air cool |
| H1075 | 1075°F (579°C) | 4 hours, air cool |
| H1100 | 1100°F (593°C) | 4 hours, air cool |
| H1150 | 1150°F (621°C) | 4 hours, air cool |
| H1150D (H1150 + 1150) | 1150°F, then 1150°F again | 4 hours, air cool + 4 hours, air cool |
| H1150M | 1400°F (760°C), then 1150°F (621°C) | 2 hours, air cool + 4 hours, air cool |
17-4PH vs 15-5PH vs 316 Stainless Steel
| Property | 17-4PH | 15-5PH | 316 |
| UNS | S17400 | S15500 | S31600 |
| Structure | Martensitic PH | Martensitic PH, ferrite-free | Austenitic |
| Hardened by | Aging | Aging | Cold work only |
| Peak tensile strength | ~200 ksi (H900) | ~200 ksi (H900) | ~75-90 ksi annealed |
| Transverse toughness | Good | Better | Excellent |
| Corrosion resistance | Similar to 304 | Similar to 304 | Best (Mo-bearing) |
| Magnetic | Yes | Yes | No (annealed) |
Corrosion Resistance Of 17-4PH
17-4PH has general corrosion resistance similar to Type 304 in the atmosphere, fresh water and mild chemicals, and it outperforms the 400-series martensitic grades. Its resistance to stress-corrosion cracking depends on the aging temperature. H900 is the most susceptible, while H1025 and higher conditions resist it much better. For sour oil-and-gas service, NACE MR0175 / ISO 15156-3 allows 17-4PH only in the double-aged H1150D condition, with a hardness limit. It can pit in stagnant seawater.
17-4PH Equivalent Designations
| Standard | Designation |
| UNS | S17400 |
| AISI / ASTM Type | 630 |
| W.Nr / EN | 1.4542 (X5CrNiCuNb16-4) |
| JIS | SUS630 |
| SAE AMS | 5604, 5643 |
| ASTM | A564 (bar), A693 (plate/sheet), A705 (forgings) |
| NACE | MR0175 / ISO 15156-3 (H1150D) |
Select AMS
| AMS Number | Alloy | Type | UNS | Cross Ref. Spec | Misc./Shape | |
|---|---|---|---|---|---|---|
| AMS 5604 Plate | 17-4PH | Stainless Steel | S17400 | - | Plate |
|
| AMS 5604 Sheet | 17-4PH | Stainless Steel | S17400 | - | Sheet |
|
| AMS 5604 Strip | 17-4PH | Stainless Steel | S17400 | - | Strip |
|
| AMS 5643 Bar | 17-4PH | Stainless Steel | S17400 | - | Bar |
|
| AMS 5643 Forging | 17-4PH | Stainless Steel | S17400 | - | Forging |
|
| AMS 5643 Ring | 17-4PH | Stainless Steel | S17400 | - | Ring |
|
| AMS 5643 Tubing | 17-4PH | Stainless Steel | S17400 | - | Tubing |
|
| AMS 5643 Wire | 17-4PH | Stainless Steel | S17400 | - | Wire |
|
Request a Quote
Metal Weight Calculator
0 Lbs