COMPREHENSIVE TECHNICAL ANALYSIS AND DATASHEET OF 17-4 PH (UNS S17400) FASTENING SYSTEMS
17-4 PH (Precipitation Hardening), also recognized as Type 630 or UNS S17400, is a highly versatile chromium-nickel-copper martensitic stainless steel. It is engineered to provide an exceptional combination of high tensile strength, extreme surface hardness, and a level of corrosion resistance that approaches that of austenitic 304 stainless steel.
The true advantage of 17-4 PH lies in its heat treatment flexibility. Supplied in the solution annealed state (Condition A), it can be readily machined and subsequently age-hardened at relatively low temperatures (900°F to 1150°F) to achieve specific mechanical properties without significant distortion or scaling. This makes it an indispensable fastening material for aerospace, petrochemical, and marine environments requiring high strength-to-weight ratios and structural reliability.
■ Product Overview & Specifications
17-4 PH fastening systems can be custom-tailored to exact project requirements through specific thermal aging cycles, ranging from Condition H900 (maximum strength and hardness) to Condition H1150-M (maximum ductility and impact toughness).
| Material Classification | Precipitation-Hardening Martensitic Stainless Steel |
|---|---|
| UNS Designation | S17400 (Type 630) |
| Microstructure | Martensitic |
| Magnetic State | Strongly Magnetic |
| Density | ~7.80 g/cm³ (0.282 lb/in³) |
| Size Range | Metric: M6 to M100 | Imperial: 1/4" to 4" Custom CNC machined profiles available upon request. |
| Thread Types | UNC, UNF, 8UN, Metric Coarse, Metric Fine |
| Strengthening Method | Solution Annealing + Low-Temperature Ageing (Precipitation) |
■ Proprietary Datasheet Download (GATED)
Access professional-grade technical data for 17-4 PH, including heat treatment cycle times, Charpy V-notch impact charts for various conditions, and exact dimensional tolerances.
17-4 PH (S17400) — Complete Technical Datasheet
Contains detailed condition mapping (H900, H1025, H1075, H1150), precise thermal expansion coefficients, and gall-resistant installation values for severe service applications.
⬇ DOWNLOAD DATASHEET■ MTC Integration Section
To guarantee the precise mechanical properties required for high-stress applications, strict lot control and heat treatment verification are paramount.
- EN 10204 Type 3.1: Detailed reporting of actual ladle chemical analysis, room-temperature mechanical testing (based on requested aging condition), and final hardness mapping.
- EN 10204 Type 3.2: Third-party witness certification (e.g., ABS, DNV, TUV) facilitated for marine and critical offshore structural bolting.
■ Chemical Composition (UNS S17400)
The defining characteristic of this alloy is the integration of Copper (Cu) and Columbium/Niobium (Cb/Nb), which trigger the precipitation-hardening reaction during the secondary aging process.
| Chromium (Cr) | Nickel (Ni) | Copper (Cu) | Manganese (Mn) | Silicon (Si) | Columbium (Cb/Nb) + Ta | Carbon (C) |
|---|---|---|---|---|---|---|
| 15.0 – 17.5 | 3.00 – 5.00 | 3.00 – 5.00 | 1.00 Max | 1.00 Max | 0.15 – 0.45 | 0.07 Max |
*Phosphorus (0.040 Max) and Sulfur (0.030 Max) are tightly controlled to preserve toughness.
■ Mechanical Properties (By Common Heat Treatment Conditions)
The mechanical properties of 17-4 PH are entirely dependent on the selected aging temperature. Lower aging temperatures yield maximum strength, while higher temperatures optimize ductility and impact resistance.
| Property | Condition H900 (Max Strength) | Condition H1025 | Condition H1150 (Max Ductility) |
|---|---|---|---|
| Tensile Strength (Min) | 190 ksi (1310 MPa) | 155 ksi (1070 MPa) | 135 ksi (930 MPa) |
| Yield Strength (0.2% Offset, Min) | 170 ksi (1170 MPa) | 145 ksi (1000 MPa) | 105 ksi (725 MPa) |
| Elongation in 2" (Min) | 10% | 12% | 16% |
| Reduction of Area (Min) | 35% | 45% | 50% |
| Hardness (Rockwell C) | 40 HRC Min | 35 HRC Min | 28 HRC Min |
■ Equivalent Grades & Designations
| Standard / System | Designation |
|---|---|
| UNS Designation | S17400 |
| Common Trade Name | 17-4 PH, Type 630 Stainless |
| European Equivalent | EN 1.4542 / X5CrNiCuNb16-4 |
| ASTM Specifications | ASTM A564 Grade 630 |
■ Applications & Industries
17-4 PH bridges the gap between high-strength carbon steels and highly corrosion-resistant austenitic stainless steels, making it ideal for:
- Aerospace & Defense: Aircraft structural components, landing gear fastening, and high-stress missile hardware.
- Marine & Offshore: Pump shafts, valve stems, and boat shafting where fatigue strength in corrosive environments is vital.
- Chemical & Food Processing: High-pressure reactor bolting and highly stressed rotating equipment.
- Nuclear Engineering: Reactor internal components and heavy-duty structural anchoring.
■ Compatible Fastener Assemblies
When selecting mating components for 17-4 PH bolts or studs, extreme care must be taken to prevent thread galling (cold welding), which is a common issue with stainless alloys under high torque.
| External Threads (17-4 PH Studs/Bolts) | Recommended Mating Component (Nuts) |
|---|---|
| 17-4 PH Condition H900 | 17-4 PH Heavy Hex Nuts (Requires heavy lubrication/anti-seize) |
| 17-4 PH Any Condition | Nitronic 60 (UNS S21800) Nuts (Best for anti-galling performance) |
■ Torque & Installation Guidelines
Because 17-4 PH has significantly higher yield strength than standard 304/316 stainless, it can support much higher clamping forces. However, premium anti-seize lubrication is strictly required to prevent thread failure.
| Nominal Diameter | Threads Per Inch (UNC) | Target Torque (H900/H1025) — Lubricated (ft-lbs) |
|---|---|---|
| 1/2" | 13 | 65 - 80 |
| 5/8" | 11 | 130 - 150 |
| 3/4" | 10 | 230 - 270 |
| 1" | 8 | 550 - 650 |
■ Why Choose Ananka Group?
Ananka Group provides absolute precision in the manufacturing and thermal processing of precipitation-hardening alloys.
- In-House Heat Treatment Management: Complete control over solution annealing and specific aging cycles (H900 to H1150M) to guarantee your exact mechanical requirements.
- Machining Before Aging: Fasteners can be machined in the softer Condition A and subsequently aged, resulting in virtually no scaling or dimensional distortion.
- Advanced Traceability: 100% heat lot tracking mapped back to the original steel mill, ensuring metallurgical authenticity.
- Customization: Capability to manufacture complex engineered bolting, double-end studs, and custom socket products.
■ Frequently Asked Questions
1. What does "17-4" stand for?
The name is derived from its approximate chemical composition: roughly 17% Chromium and 4% Nickel, combined with Copper to allow for precipitation hardening.
2. How does 17-4 PH corrosion resistance compare to standard stainless steels?
17-4 PH offers excellent corrosion resistance that is generally comparable to 304 stainless steel, and superior to standard 400-series martensitic steels. However, for severe chloride/marine environments, 316 stainless or duplex alloys may be required.
3. Is 17-4 PH magnetic?
Yes. Unlike austenitic stainless steels (like 304 or 316) which are non-magnetic, 17-4 PH has a martensitic microstructure and is strongly magnetic in all conditions.
4. What is the difference between Condition A and Condition H900?
Condition A is the base "Solution Annealed" state where the metal is softer and optimal for machining. Condition H900 is achieved by aging the Condition A material at 900°F (482°C) for one hour, resulting in the alloy's maximum possible strength and hardness.
