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Alloy Technical Data Sheet
Type 17-7PH® Stainless Steel
Precipitation-Hardening Stainless Steel · UNS S17700
Chromium-nickel-aluminum precipitation-hardening stainless — formed soft, then hardened at low temperature to very high strength with minimal distortion.
General Properties
17-7PH® (S17700) is a chromium-nickel-aluminum precipitation-hardening stainless steel for applications requiring high strength and a moderate level of corrosion resistance, including aerospace components and springs.
It can be formed in a soft austenitic condition and hardened to high strength by low-temperature heat treatments, which cause far less distortion than conventional quench-and-temper hardening. Vacuum-arc or electroslag remelted material is available for added fatigue resistance in cyclically stressed parts.
Chemical Composition
| Element | 17-7PH® |
|---|---|
| Carbon | 0.09 |
| Manganese | 1.00 |
| Phosphorus | 0.040 |
| Sulfur | 0.030 |
| Silicon | 1.00 |
| Chromium | 16.00–18.00 |
| Nickel | 6.50–7.75 |
| Aluminum | 0.75–1.50 |
| Iron | Balance |
Mechanical Properties — Condition A (Annealed)
| Property | Annealed (A) | RH 950 | TH 1050 |
|---|---|---|---|
| Tensile, psi (MPa) | 130,000 (900) | 220,000 (1520) | 190,000 (1310) |
| 0.2% Yield, psi (MPa) | 45,000 (310) | 200,000 (1380) | 160,000 (1100) |
| Elongation, % | 30 | 9 | 10 |
| Hardness, Rockwell | B85 | C46 | C42 |
Data are typical and do not necessarily represent minimum or maximum values. Each lot may vary.
Mechanical Properties — Condition C
| Property | Condition C | CH 900 |
|---|---|---|
| Tensile, psi (MPa) | 200,000 (1380) | 240,000 (1655) |
| 0.2% Yield, psi (MPa) | 175,000 (1205) | 230,000 (1585) |
Data are typical and do not necessarily represent minimum or maximum values. Each lot may vary.
Heat Treatment
Hardening from Condition A takes two steps: an austenite-conditioning treatment that lets the austenite transform to martensite, then a precipitation-hardening (aging) treatment.
- TH 1050: condition at 1400 °F (760 °C) — martensite forms on cooling to near room temperature — then age at 1050 °F (565 °C).
- RH 950: condition at 1750 °F (955 °C), complete the transformation by holding at −100 °F (−73 °C), then age at 950 °F (510 °C).
- CH 900: Condition C material, already transformed by heavy cold work, is aged directly at 900 °F (482 °C).
Aging can be driven past peak strength; higher temperatures or longer times produce lower strength.
Physical Properties
| Melting range | 2560–2625 °F (1404–1440 °C) |
|---|---|
| Density | 0.282 lb/in³ (7.80 g/cm³) |
| Specific gravity | 7.81 |
| Modulus of elasticity (tension) | 29 × 10⁶ psi (200 GPa) |
| Specific heat, 32–212 °F | 0.12 Btu/lb·°F (500 J/kg·K) |
| Thermal conductivity, hardened, 70–300 °F | ≈ 9.5 Btu/hr·ft·°F (16.5 W/m·K) |
| Electrical resistivity | ≈ 80 microhm-cm, annealed or hardened |
Thermal Expansion, 70–200 °F (21–93 °C)
| Condition | in/in/°F | cm/cm/°C |
|---|---|---|
| Annealed | 8.5 × 10⁻⁶ | 15.3 × 10⁻⁶ |
| RH 950 | 5.7 × 10⁻⁶ | 10.3 × 10⁻⁶ |
| TH 1050 | 5.6 × 10⁻⁶ | 10.1 × 10⁻⁶ |
Magnetic Permeability
Weakly ferromagnetic when annealed; strongly ferromagnetic in Conditions RH 950 and TH 1050.
Corrosion Resistance
Corrosion resistance is comparable to Type 304 in most media and generally superior to the hardenable 400 series stainless steels.
Values are typical or specification minimums as noted, provided for information only, and should not be used as design limits or as a guarantee of properties for any particular lot or application. Certified test reports are supplied with each order. 17-7PH® is a registered trademark of Cleveland-Cliffs Steel Corporation.Rev. 10/2026