Products Features
Extremely high strength and excellent elasticity performance (core advantage)
The core advantage of 17-7PH lies in its ability to achieve extremely high strength and elastic limit through cold working combined with aging treatment. After solution treatment + cold working (cold rolling, cold drawing) + aging at 480°C, it exhibits a tensile strength ≥ 1170 MPa (exceeding 1400 MPa under certain heat treatment conditions), yield strength ≥ 1000 MPa, and hardness ≥ 38 HRC. Its modulus of elasticity (approximately 200 GPa) is comparable to that of austenitic stainless steel, but its strength level is significantly higher. This makes it an ideal material for manufacturing products requiring high elasticity and strength, such as high-stress springs, bellows, and diaphragm sheets.
Excellent fatigue resistance
17-7PH exhibits excellent fatigue resistance under high-stress cyclic loading conditions. Its high-cycle fatigue limit is significantly superior to that of 304 and 316 austenitic stainless steels, offering distinct advantages in spring and fastener applications. The combination of its high tensile strength and good toughness allows it to maintain a long service life under cyclic stress conditions. This characteristic makes it an ideal material choice for applications with strict fatigue life requirements, such as aerospace fasteners, automotive suspension springs, and medical device springs.
Good corrosion resistance
17-7PH exhibits excellent resistance to uniform corrosion in atmospheric environments, fresh water, and mildly corrosive media due to a dense, stable, and self-healing Cr₂O₃ oxide film formed spontaneously on its surface. Its corrosion resistance is superior to that of 18-8 type austenitic stainless steels (e.g., 304), offering good pitting and stress corrosion cracking resistance in marine environments and chloride solutions. 17-7PH also demonstrates good corrosion resistance in media such as nitric acid, organic acids, and alkaline solutions. This property makes it an ideal material choice for applications with high corrosion resistance requirements, including marine engineering, chemical processing equipment, and medical devices.
Good formability
17-7PH exhibits excellent cold working formability in the solution-annealed condition (Condition A), allowing it to undergo various cold forming processes such as cold rolling, cold drawing, stamping, and bending. Its formability is superior to that of martensitic precipitation-hardening stainless steels (e.g., 17-4PH), enabling the production of complex-shaped parts in the solution-annealed state. These parts can then achieve the final high strength and high elasticity through cold working followed by aging treatment. This characteristic makes it an ideal material for products that require pre-forming and subsequent strengthening, such as bellows, diaphragms, and stamped components.
Good welding performance
17-7PH exhibits good weldability and can be connected using various welding methods such as TIG, MIG, and resistance welding. When welding, attention should be paid to controlling the heat input to avoid grain coarsening and performance degradation in the heat-affected zone. After welding, solution treatment followed by aging treatment is typically required to restore the strength and corrosion resistance of the weld area. It is recommended to use matching filler materials (such as 17-7PH wire of the same material or 304L/316L wire) to ensure that the weld properties meet the usage requirements.
Good hot working properties
17-7PH exhibits excellent hot working properties and can be formed through hot forging, hot rolling, hot extrusion, and other hot working processes within a temperature range of 950-1150°C. After hot working, solution treatment (approximately 1050-1100°C) is required to achieve optimal cold working performance and subsequent aging response.
Technical Specifications
Chemical Composition(ASTM A693 / UNS S17700)
|
Element |
Standard Requirements |
Notes |
|
Cr |
16.0 - 18.0% |
Core elements form a dense passivation film, providing corrosion resistance |
|
Ni |
6.5 - 7.75% |
Austenite stabilizing elements provide a basis for semi-austenitic microstructures |
|
Al |
0.75 - 1.50% |
Precipitate and strengthen elements, forming NiAl precipitates with Ni to provide high strength |
|
Mn |
≤ 1.0% |
Deoxidizer, strictly controlled |
|
Si |
≤ 1.0% |
Deoxidizer, strictly controlled |
|
C |
≤ 0.09% |
Strictly control to prevent the precipitation of carbides, which can damage corrosion resistance and toughness |
|
P |
≤ 0.040% |
Impurity elements, strictly controlled |
|
S |
≤ 0.030% |
Impurity elements, strictly controlled |
|
Fe |
Remaining quantity (≈ 74%) |
Matrix element |
Physical Properties
|
Property |
Value/Range |
Test Conditions |
|
Density |
7.65 g/cm³ |
Room Temperature (20°C) |
|
Melting Point |
≈ 1415°C |
- |
|
Thermal Conductivity |
≈ 15 W/(m·K) |
Room Temperature |
|
Coefficient of thermal expansion (20-100°C) |
≈ 11.0 × 10⁻⁶ /K |
- |
|
Resistivity |
≈ 0.80 μΩ·m |
Room Temperature |
|
Elastic modulus (Young's modulus) |
≈ 200 GPa |
Room Temperature |
|
Poisson's ratio |
≈ 0.27 |
Room Temperature |
|
Magnetic |
Ferromagnetic |
The semi-austenitic + martensitic microstructure is magnetic. |
Mechanical Properties (Typical values, ASTM A693 / AMS 5528)
|
Performance |
Condition A (Solid Solution State) |
TH 1050 (Cold Worked + Aging) |
RH 950 (Cold Worked + Aging) |
Specification |
|
Tensile Strength |
≈ 850 MPa |
≥ 1170 MPa |
≥ 1310 MPa |
ASTM A693 / AMS 5528 |
|
Yield Strength (0.2% Offset) |
≈ 310 MPa |
≥ 1000 MPa |
≥ 1170 MPa |
ASTM A693 / AMS 5528 |
|
Elongation |
≥ 35% |
≥ 6% |
≥ 5% |
ASTM A693 / AMS 5528 |
|
Hardness (Rockwell C) |
≈ 25 HRC |
≥ 38 HRC |
≥ 41 HRC |
- |
Note: The strength of 17-7PH is achieved through the process route of 'solution treatment + cold working + aging'. Condition A refers to the solution-treated state, suitable for forming and machining. TH 1050 and RH 950 are two different aging processes, which can be selected based on the required strength grade of the customer. Specific properties can be adjusted according to the heat treatment condition required by the customer.
Corrosion Resistance (Typical Value)
|
Medium |
Concentration |
Temperature |
Corrosion rate |
Rating |
|
Seawater |
- |
Room temperature to high temperature |
Ignored |
Excellent |
|
Atmospheric environment |
- |
Room Temperature |
Ignored |
Excellent |
|
Nitric acid (HNO₃) |
≤ 40% |
Room Temperature |
＜0.05 |
Excellent |
|
Sulfuric acid (H₂SO₄) |
≤ 10% |
Room Temperature |
＜0.1 |
Good |
|
Hydrochloric acid (HCl) |
Low concentration |
Room Temperature |
＜0.1 |
Good |
|
Sodium hydroxide (NaOH) |
- |
Room Temperature |
Ignored |
Excellent |
|
Organic acids (such as acetic acid, citric acid, etc.) |
- |
Room Temperature |
Ignored |
Excellent |
Note: The corrosion resistance of 17-7PH is superior to that of 304 austenitic stainless steel in most environments and performs well in marine and chloride environments. Its resistance to stress corrosion cracking is better than that of 18-8 type austenitic stainless steel, but its corrosion resistance is limited in strongly corrosive media such as high-temperature concentrated hydrochloric acid and hydrofluoric acid.
High-temperature performance
17-7PH (TH 1050 aged condition) maintains high strength at moderate temperatures:
|
Temperature |
Tensile Strength (MPa) |
Performance retention rate |
|
Room temperature (20°C) |
≥ 1170 |
100% |
|
200°C |
≈ 1070 |
≥ 91% |
|
300°C |
≈ 980 |
≥ 84% |
|
400°C |
≈ 870 |
≥ 74% |
Long-term thermal stability and organizational stability:
17-7PH exhibits good microstructural stability and stable precipitation-hardening phases when in long-term service at temperatures ≤ 300°C.
Note that:
Prolonged exposure at temperatures between 300-450°C may lead to overaging, resulting in a decrease in strength; therefore, long-term use within this temperature range is not recommended. At temperatures above 500°C, the precipitate phases begin to coarsen, causing a significant reduction in strength.
Antioxidant performance:
17-7PH can form a protective oxide layer below 650°C. For long-term service at higher temperatures, it is recommended to evaluate oxidation weight gain and performance degradation.
Heat Treatment Regime
The heat treatment of 17-7PH has a decisive impact on the final microstructure and properties, with common specifications as follows:
1.Solution treatment (Condition A, for obtaining the best cold working forming performance):
Heat to 1050-1100°C, hold for a sufficient time (approximately 15-30 minutes per inch of thickness), and then quench rapidly in air or water. This will produce a semi-austenitic microstructure, preparing it for subsequent cold working and aging.
2. Cold working (for strength enhancement):
Cold working deformation such as cold rolling, cold drawing, and cold stamping is performed in the solution-treated state, with a deformation amount generally ranging from 50% to 70%. Cold working transforms the semi-austenitic structure into a martensitic structure, providing a strengthening basis for subsequent aging treatment.
3. Aging Treatment (for obtaining final performance):
|
Time-effectiveness conditions |
Temperature |
Time |
Typical tensile strength |
Application scenarios |
|
TH 1050 |
480-510°C |
1-2 hours |
≥ 1170 MPa |
High strength plus good elasticity, springs, fasteners |
|
RH 950 |
565-595°C |
1-2 hours |
≥ 1310 MPa |
Maximum strength + maximum hardness |
|
CH 900 |
455-495°C |
1-2 hours |
≥ 1400 MPa |
Ultra-high strength + high hardness |
Note:
- The final performance of 17-7PH is highly dependent on the complete process chain of 'solution treatment + cold working + aging', and controlling the cold working deformation amount is crucial.
- Heat treatment should be carried out under vacuum or inert gas protection to prevent surface oxidation and decarburization.
- Deviation in temperature and time can significantly affect the final mechanical properties and must be strictly controlled.
Workability
The machinability of 17-7PH depends on its heat treatment condition:
|
Processing Method |
Recommended Parameters/ Methods |
Notes |
|
Cold Working (Solution Annealed Condition) |
Cold rolling, cold drawing, stamping, bending |
The solution-treated condition offers the best formability, and strength increases significantly after work hardening. |
|
Mechanical Processing (Solution-Annealed State) |
Turning, milling, drilling |
Select carbide cutting tools and appropriate cutting parameters |
|
Mechanical Processing (Solution-Annealed State) |
Grinding, Electrical Discharge Machining (EDM) |
The material exhibits high hardness at room temperature; grinding or electrical discharge machining is recommended. |
|
Welding |
TIG, MIG, Resistance Welding |
It is recommended to perform solution treatment followed by aging treatment after welding to restore performance. |
|
Hot working |
Forging, Hot Rolling (950-1150°C) |
Solution treatment is required after hot processing |
Applicable Media
1. Atmospheric environment: Excellent corrosion resistance, no need for surface coating protection.
2. Seawater and chloride solutions: Good pitting corrosion and stress corrosion cracking resistance.
3. Oxidizing acids: Such as nitric acid (≤40%), excellent corrosion resistance.
4. Weak reducing acids: Such as dilute sulfuric acid (≤10%), dilute hydrochloric acid (low concentration), can be withstood at room temperature.
5. Organic acids: Acetic acid, citric acid, formic acid, etc.
6. Alkaline solutions: Sodium hydroxide, potassium hydroxide, etc.
7. Aviation kerosene, hydraulic oil: Good compatibility.
Note: 17-7PH is not resistant to strongly corrosive media such as hydrofluoric acid, high-temperature concentrated hydrochloric acid, etc.
17-7PH is suitable for applications with comprehensive requirements of high strength, high elasticity, and corrosion resistance, and is recommended for the following fields:
Application Fields
-
Springs and Elastic Elements (Core Applications)
● High-stress helical springs, wave springs, and disc springs
● Corrugated tubes, diaphragms, and bellows
● Precision instrument elastic elements
● Car suspension springs, valve springs -
Aerospace
● High-strength fasteners, rivets
● Aircraft skin, honeycomb structure
● Engine accessories, hydraulic lines
● Spacecraft structural components -
Medical devices
● Surgical instruments, medical springs
● Dental instruments, orthopedic implants (non-weight-bearing)
● Precision components of medical devices -
Chemical Engineering and Petroleum and Natural Gas
● Chemical equipment fasteners, pump and valve components
● Pressure vessel liners, heat exchanger plates
● Oil Well Downhole Tools -
Precision Instruments and Electronics
● Precision springs, connectors
● Sensor elements, lead frames
● Electronic device structural components -
Automobiles and High-Performance Industry
● High-performance engine valve springs
● Transmission spring, clutch spring
● Injection System Components -
Marine engineering
● Ship fasteners, seawater pump valve components
● Offshore platform structural components
Delivery and Customization
We offer flexible and reliable supply chain solutions to ensure you receive 17-7PH 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 Φ0.5-10mm |
|
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 , Fixed Length Cutting |
Precision strip materials, stamping coil stock, laminated blanking, non-standard width, special protective film |
Precision drawing, 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 17-7PH?
Q: What is the difference between 17-7PH and 17-4PH (630)? How to choose?
Q: What is the difference between 17-7PH and 304 stainless steel? How to choose between them?
Q: What is the maximum service temperature for 17-7PH?
Q: What is the welding performance of 17-7PH?
Q: Can 17-7PH replace 304 stainless steel?
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