Products Features
Ultra-high strength and hardness (core advantage)
The core advantage of 17-4PH lies in its ability to achieve extremely high strength and hardness through simple heat treatment. After solution treatment, the alloy exhibits a low-carbon martensitic structure with a hardness of approximately 28-32 HRC. Precipitation hardening can be obtained via a single aging treatment at 480-620°C, and the strength level can be flexibly adjusted by varying the aging temperature.
Comparison of mechanical properties at different aging temperatures
|
Aging Condition |
Tensile Strength |
Yield Strength(0.2%) |
Elongation |
Hardness |
|
480℃ (H900) |
≥ 1310 MPa |
≥ 1180 MPa |
≥ 10% |
≥ 40 HRC |
|
550℃ (H1025) |
≥ 1060 MPa |
≥ 1000 MPa |
≥ 12% |
≥ 35 HRC |
|
580℃ (H1075) |
≥ 1000 MPa |
≥ 865 MPa |
≥ 13% |
≥ 31 HRC |
|
620℃ (H1150) |
≥ 930 MPa |
≥ 725 MPa |
≥ 16% |
≥ 28 HRC |
Its yield strength is 3-5 times that of 304 stainless steel (≈220 MPa) and 1.2-1.5 times that of 17-7PH (semi-austenitic precipitation-hardening stainless steel), which can significantly reduce wall thickness to achieve structural lightweighting and cost optimization.
Good corrosion resistance
The corrosion resistance of 17-4PH is comparable to that of 304 stainless steel (SS 302), performing well in atmospheric environments, fresh water, diluted acids (such as nitric acid and acetic acid), and salt solutions. Its high chromium content (15-17.5%) forms a dense Cr₂O₃ passivation film, providing fundamental corrosion resistance. Nitric acid passivation (ASTM A967) can further increase the thickness and stability of the passivation film, significantly enhancing pitting resistance. In marine high-salt fog environments, it is recommended to combine surface passivation, gap sealing, or design optimization to reduce the risk of pitting and crevice corrosion.
However, it should be noted that 17-4PH is relatively sensitive to stress corrosion cracking (SCC) in acidic environments containing hydrogen sulfide (H₂S). It exhibits significant SCC sensitivity in NACE standard tests, with fracture surfaces displaying brittle cleavage characteristics and crack propagation predominantly intergranular. Long-term use in high-temperature environments with high concentrations of chloride ions requires careful evaluation.
Excellent heat treatment simplicity
One of the most significant advantages of 17-4PH is its simple heat treatment process-the 'single-step aging hardening' property is a core advantage for its engineering applications. Unlike semi-austenitic precipitation-hardening stainless steels (such as 17-7PH), which require complex austenite stabilization and cryogenic treatment, 17-4PH forms a martensitic structure after solution treatment. It only needs a single aging treatment to achieve strengthening, eliminating the need for complex quenching processes, thereby significantly reducing processing costs and deformation risks.
Solution treatment:
Heat to 1020-1060°C, hold at temperature, then quench rapidly (oil quenching or air cooling) to obtain a martensitic structure.
Timed heat treatment:
Select a temperature within the range of 480-620°C for single aging. After holding at this temperature for 1-4 hours, air cool. Strengthening is achieved through the dispersed precipitation of the ε-Cu phase.
Good machining and welding properties
17-4PH exhibits good hot and cold working properties, allowing it to be forged, rolled, and stamped into shape. In the solution-annealed condition, it has moderate hardness (≤363 HB/≤38 HRC) and can be formed through conventional machining processes such as turning, milling, drilling, and grinding.
It has good welding properties and can be connected using conventional welding methods (TIG, MIG, SMAW). When welding, it is recommended to use matching 17-4PH welding materials, and the mechanical properties of the heat-affected zone can be restored through aging heat treatment after welding. Compared with conventional martensitic stainless steels, 17-4PH has significantly improved weldability and toughness due to its ultra-low carbon design and niobium addition.
Note: This alloy is ferromagnetic, unlike austenitic stainless steels, and is therefore not suitable for applications requiring non-magnetism (such as MRI equipment and precision electronic instruments).
Excellent fatigue and corrosion fatigue resistance properties
17-4PH exhibits excellent fatigue resistance. Its combination of high strength and good toughness enables it to perform exceptionally well under cyclic loading conditions. Particularly in corrosive environments, its corrosion fatigue resistance is superior to that of conventional martensitic stainless steels and some austenitic stainless steels. This property makes it an ideal material for components subjected to the dual effects of alternating loads and corrosive environments, such as offshore platforms, turbine blades, and pump shafts.
Technical Specifications
Chemical Composition(ASTM A564 / UNS S17400)
|
Element |
Standard Requirements |
Notes |
|
Cr |
15.0 - 17.5% |
Core elements that form a dense passivation film, providing basic corrosion resistance |
|
Ni |
3.0 - 5.0% |
Austenitizing elements, adjust the martensitic transformation point, improve toughness |
|
Cu |
3.0 - 5.0% |
The core precipitated hardening elements, which form ε-Cu phases during aging treatment, resulting in dispersion strengthening |
|
Nb (+Ta) |
0.15 - 0.45% |
Carbide-forming elements (NbC) refine grains, participate in precipitation strengthening, and prevent intergranular corrosion. |
|
C |
≤ 0.07% |
Ultra-low carbon design minimizes carbide segregation to the maximum extent, ensuring weldability and toughness. |
|
Mn |
≤ 1.00% |
Deoxidizer |
|
Si |
≤ 1.00% |
Deoxidizer |
|
P |
≤ 0.040% |
Impurity elements, strictly controlled |
|
S |
≤ 0.030% |
Impurity elements, strictly controlled |
|
Fe |
Remaining quantity |
Matrix element |
Physical Properties
|
Property |
Value/Range |
Test Conditions |
|
Density |
7.75 - 7.80 g/cm³ |
Room Temperature (20°C) |
|
Melting Point |
1400 - 1440°C |
--- |
|
Resistivity |
≈ 0.80 μΩ·m |
Room Temperature |
|
Thermal Conductivity |
≈ 16 - 18 W/(m·K) |
Room Temperature |
|
Coefficient of thermal expansion (20-100°C) |
≈ 10.8 × 10⁻⁶ /K |
Room temperature to 100°C |
|
Elastic modulus (Young's modulus) |
≈ 196 - 203 GPa |
Room Temperature |
|
Poisson's ratio |
≈ 0.27 - 0.30 |
Room Temperature |
|
Magnetism |
Magnetic (ferromagnetic) |
Martensitic structure, which is ferromagnetic and can be attracted by a magnet |
Mechanical Properties (Solution heat-treated + aged condition, typical values, ASTM A564)
|
Aging Condition |
Tensile Strength |
Yield strength(0.2%) |
Elongation |
Hardness |
|
480°C (H900) |
≥ 1310 MPa |
≥ 1180 MPa |
≥ 10% |
≥ 40 HRC |
|
550°C (H1025) |
≥ 1060 MPa |
≥ 1000 MPa |
≥ 12% |
≥ 35 HRC |
|
580°C (H1075) |
≥ 1000 MPa |
≥ 865 MPa |
≥ 13% |
≥ 31 HRC |
|
620°C (H1150) |
≥ 930 MPa |
≥ 725 MPa |
≥ 16% |
≥ 28 HRC |
Note: The strength level of 17-4PH can be flexibly adjusted by aging temperature. The lower the aging temperature, the higher the strength but the lower the elongation; conversely, as the aging temperature increases, strength decreases while ductility and toughness improve.
High-temperature performance
17-4PH maintains a high level of strength within the range of ≤ 300°C, and the recommended maximum service temperature should not exceed 300°C. Beyond this temperature, the precipitation-hardening phase will gradually coarsen, leading to a decrease in strength.
|
Temperature |
Performance maintenance status |
Explanation |
|
Room Temperature (20°C) |
100%(Peak) |
The H900 alloy can achieve a tensile strength of up to 1310 MPa |
|
100°C |
≥ 90% |
The strength is well maintained |
|
200°C |
≥ 85% |
It can still maintain high strength |
|
300°C |
≥ 75% |
It is recommended to use the upper limit for a long period |
|
> 400°C |
A significant decline |
Precipitate coarsening leads to a rapid decline in strength |
Long-term thermal stability:
17-4PH exhibits good microstructural stability when in service at temperatures up to ≤ 300°C. However, upon prolonged exposure above 400°C, the ε-Cu precipitate phase gradually coarsens, leading to a decrease in strength. This alloy is not suitable for use at temperatures higher than 300°C or very low temperatures.
Heat Treatment Regimen
The final properties of 17-4PH are highly dependent on the heat treatment regimen, with common specifications as follows:
1. Solution treatment (to obtain martensitic structure):
Heat to 1020-1060°C, hold for a sufficient time (approximately 30-60 minutes per inch of thickness), and then cool rapidly (oil quench or air cool). This process results in a low-carbon martensitic structure, preparing it for subsequent aging and precipitation hardening.
2. Aging Temperature treatment (precipitation hardening to achieve the target strength grade):
Select the holding temperature based on the target strength grade.
|
Aging Condition |
Aging Temperature |
Holding Time |
Cooling method |
Target Strength Level |
|
H900 |
480°C |
1 hour |
Air-cooled |
Maximum intensity |
|
H925 |
495°C |
4 hour |
Air-cooled |
Ultra-high strength |
|
H1025 |
550°C |
4 hour |
Air-cooled |
High strength plus good toughness |
|
H1075 |
580°C |
4 hour |
Air-cooled |
Medium strength + good toughness |
|
H1150 |
620°C |
4 hour |
Air-cooled |
Optimal toughness plus corrosion resistance |
Note:
- Solution treatment should be performed before the final mechanical machining, and aging treatment can be carried out after machining to take advantage of the better machinability of the solution-treated state.
- The lower the aging temperature, the higher the strength and the lower the elongation; as the aging temperature increases, strength decreases while ductility and toughness improve.
- It is recommended to perform aging heat treatment after welding to restore the mechanical properties of the heat-affected zone.
Applicable Media
1. Atmospheric Environment: Exhibits good corrosion resistance in both normal and industrial atmospheres.
2. Freshwater: Demonstrates excellent corrosion resistance in freshwater and drinking water.
3. Dilute Acids: Shows good corrosion resistance in dilute nitric acid, dilute acetic acid, and dilute phosphoric acid.
4. Salt Spray Environment: Corrosion resistance is comparable to 304 stainless steel in marine salt spray environments; however, there is a risk of pitting and crevice corrosion. Surface treatment is recommended for use.
5. Oil and Gas Media: Suitable for oil and gas environments containing CO₂ but not H₂S; it has a higher susceptibility to stress corrosion cracking (SCC) in acidic environments with H₂S and requires careful evaluation.
6. Food Industry Media: Complies with requirements for food contact materials.
Note:
17-4PH is not resistant to extreme highly corrosive media such as high-temperature concentrated hydrochloric acid, hydrofluoric acid, and boiling sulfuric acid. In acidic environments containing hydrogen sulfide (H₂S), it has a higher susceptibility to stress corrosion cracking and is therefore not recommended for use in acidic oil and gas field environments specified by NACE standards.
17-4PH (630/UNS S17400) is specifically designed for demanding applications that require a combination of high strength, high hardness, and good corrosion resistance, and is recommended for use in the following fields:
Application Fields
-
Aerospace
Turbine blades, compressor blades, engine fasteners, landing gear components, helicopter deck components -
Offshore engineering and offshore platforms
Marine platform structural components, helicopter decks, ship propeller shafts, pump and valve parts, subsea valve assemblies, and high-salt fog environment fasteners.
Note: In marine environments, it is recommended to use passivation treatment, gap sealing, or design optimization in combination. -
Petrochemicals and Energy
Nuclear industry waste drums, nuclear power plant valve stems, high-strength bolts, reactor shaft components, corrosion-resistant environment load-bearing structures -
Food and Paper Industries
Food processing equipment, pulp and papermaking equipment -
General Machinery Manufacturing
High-strength shafts, turbine components, mechanical parts, molds
Delivery and Customization
We offer flexible and reliable supply chain solutions to ensure you receive 17-4PH materials that perfectly match your project requirements.
|
Form |
 Sheet/Plate
|
 Bar/Rod
|
 Pipe / Tube
|
 Strip/Sheet Coil
|
 Wire/Wire Rod
|
|---|---|---|---|---|---|
|
Conventional Range |
Thickness: 0.5 - 100 mm |
Diameter Φ6-500mm |
Outer diameter Φ10-300mm |
Thickness: 0.05 – 3.0 mm |
Diameter Φ0.1-10mm |
|
Customization Capability |
Hot-rolled or cold-rolled plates, ultra-thin plates (starting from 0.1mm), stamped parts, length-cutting to specified dimensions, special surface treatments (pickling, polishing) |
Forged bars, hot-rolled bars, polished bars, shaped bars, and different heat treatment conditions (solution-treated condition) |
Seamless Tubes/ Welded Tubes (Compliant with ASTM A312/ A269), Fixed-Length Cutting, U-Tubes |
Precision strip materials, stamping coil stock, laminated blanking, non-standard width, special protective film |
Precision drawing, spring wire, welding filler wire, special surface treatment |
Why Choose Us? - Reliable Engineering Technology. Dependable Delivery.
We are not just a supplier, but a trusted materials partner for you in China.
Vertically Integrated Production
Own 20,000㎡ facility with 10+ automated lines (8,000+ tons/year). In-house tooling & die center enables rapid customization and effective cost control - no middleman markup.
Strict Quality Control at Every Stage
Full traceability across key QC checkpoints throughout production. 100% compliant with ASTM/ASME, EN, and GB standards. Material test reports available with every shipment.
Reliable Delivery & Export Packaging
10+ years exporting to Europe, North America, Southeast Asia & Middle East with waterproof and anti-rust protection, combined with flexible shipping options ensures safe and on-time arrival.
Sample Validation Before Mass Production
We provide free samples for quality verification, allowing you to place bulk orders only after approval. We ensure consistency from sample to mass production by accurate dimensional measurement and transparent manufacturing.
FAQ
Q: What are the main advantages of 17-4PH?
Q: What is the difference between 17-4PH and 304 stainless steel? How to choose between them?
Q: What is the maximum service temperature for 17-4PH?
Q: What is the welding performance of 17-4PH?
Q: What is the corrosion resistance of 17-4PH?
Q: Can 17-4PH replace 304 or 316L?
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