Stainless Steel 17-4 PH
Stainless Steel 17-4 PH (UNS S17400 / EN 1.4542)
Stainless Steel 17-4 PH (UNS S17400 / EN 1.4542) is a precipitation-hardening martensitic stainless steel that combines very high mechanical strength, hardness, good corrosion resistance, and dimensional stability.
The designation 17-4 PH refers to its nominal composition of approximately 17% chromium and 4% nickel, while PH stands for Precipitation Hardening. The addition of copper and niobium allows the material to develop high strength through controlled heat treatment.
Unlike conventional austenitic stainless steels, 17-4 PH can achieve different combinations of strength, hardness, toughness, and ductility through solution treatment and aging. This makes it particularly valuable for components that require both corrosion resistance and high mechanical performance.
Stainless Steel 17-4 PH is widely used in aerospace, oil & gas, petrochemical, power generation, marine, pump and valve manufacturing, and mechanical engineering.
Emirerri Steel supplies Stainless Steel 17-4 PH in sheets, plates, round bars, forgings, tubes, pipes, flanges, and machined components for projects across Tunisia, Algeria, Morocco, Libya, and international markets.
Key Features
- Precipitation-hardening martensitic stainless steel
- Very high mechanical strength
- High hardness after aging
- Good general corrosion resistance
- Good wear resistance
- Good fatigue resistance
- Good dimensional stability
- Good oxidation resistance
- Good machinability in suitable conditions
- Good weldability with appropriate procedures
- Multiple heat-treatment conditions
- Excellent strength-to-weight ratio
Specifications
| Specification | Details |
|---|---|
| Grade | Stainless Steel 17-4 PH |
| UNS | S17400 |
| Werkstoff Number | 1.4542 |
| EN Designation | X5CrNiCuNb16-4 |
| Type | Martensitic Precipitation-Hardening Stainless Steel |
| Main Alloying Elements | Chromium, Nickel, Copper, Niobium |
| Common Standards | ASTM A564, ASTM A693, ASTM A705, EN 10088 |
| Heat Treatment Conditions | H900, H925, H1025, H1075, H1150 |
| Product Forms | Sheet, Plate, Round Bar, Forgings, Tube, Pipe, Machined Components |
Equivalent Grades of Stainless Steel 17-4 PH
| Standard | Equivalent Grade |
|---|---|
| ASTM / UNS | 17-4 PH / S17400 |
| EN | 1.4542 |
| EN Designation | X5CrNiCuNb16-4 |
| DIN | X5CrNiCuNb16-4 |
| JIS | SUS630 |
| AISI | 630 |
| AFNOR | Z5CNU17-4 |
Available Sizes
17-4 PH Sheets & Plates
- Thickness: 0.5 to 100 mm
- Width: Up to 2500 mm
- Length: Up to 12000 mm
17-4 PH Round Bars
- Diameter: 6 to 500 mm
17-4 PH Tubes & Pipes
- Outside Diameter: 6 to 610 mm
- Wall Thickness: According to applicable standard and project requirements
Actual availability depends on product form, heat-treatment condition, applicable standard, and project specifications.
Stainless Steel 17-4 PH Chemical Composition
| Element | Composition (%) |
|---|---|
| Chromium (Cr) | 15.0 – 17.5 |
| Nickel (Ni) | 3.0 – 5.0 |
| Copper (Cu) | 3.0 – 5.0 |
| Niobium + Tantalum (Nb + Ta) | 0.15 – 0.45 |
| Manganese (Mn) | ≤ 1.00 |
| Silicon (Si) | ≤ 1.00 |
| Carbon (C) | ≤ 0.07 |
| Phosphorus (P) | ≤ 0.040 |
| Sulfur (S) | ≤ 0.030 |
| Iron (Fe) | Balance |
Stainless Steel 17-4 PH Mechanical Properties
Mechanical properties depend strongly on the selected aging condition.
| Condition | Tensile Strength | Yield Strength |
|---|---|---|
| H900 | ≈ 1310 MPa min. | ≈ 1170 MPa min. |
| H925 | ≈ 1170 MPa min. | ≈ 1070 MPa min. |
| H1025 | ≈ 1070 MPa min. | ≈ 1000 MPa min. |
| H1075 | ≈ 1000 MPa min. | ≈ 860 MPa min. |
| H1150 | ≈ 930 MPa min. | ≈ 795 MPa min. |
H900 generally provides very high strength and hardness, while H1150 provides a better balance of toughness and ductility.
Stainless Steel 17-4 PH Physical Properties
| Property | Approximate Value |
|---|---|
| Density | 7.75 g/cm³ |
| Modulus of Elasticity | ≈ 200 GPa |
| Thermal Conductivity | ≈ 17 W/m·K |
| Specific Heat Capacity | ≈ 460 J/kg·K |
| Thermal Expansion Coefficient | ≈ 10.8 × 10⁻⁶ /°C |
| Melting Range | ≈ 1400 – 1450°C |
| Magnetic Properties | Magnetic |
Types of Stainless Steel 17-4 PH Products
17-4 PH Sheets & Plates
Used for high-strength mechanical components, pressure equipment, aerospace components, and industrial fabrication.
17-4 PH Round Bars
Used for shafts, pins, bolts, valve stems, pump components, and precision-machined parts.
17-4 PH Forgings
Used for components requiring high mechanical strength, toughness, and metallurgical integrity.
17-4 PH Tubes & Pipes
Used in selected fluid-control, instrumentation, energy, and industrial applications.
17-4 PH Flanges & Components
Used where high strength, hardness, and corrosion resistance are required.
Corrosion Resistance
Stainless Steel 17-4 PH provides good general corrosion resistance in atmospheric and many industrial environments.
It offers resistance to:
- Atmospheric corrosion
- Oxidation
- Many industrial environments
- Selected chemical environments
- General corrosion
- Some stress-corrosion conditions
Corrosion resistance can vary with heat-treatment condition. For highly aggressive chloride environments, materials such as 316L, Duplex 2205, or Super Duplex 2507 may be more suitable depending on service conditions.
Heat Resistance
17-4 PH offers good oxidation resistance and retains useful mechanical strength at moderate elevated temperatures.
However, prolonged exposure to certain temperatures can alter its microstructure and mechanical properties. Therefore, service temperature should be carefully considered during material selection.
For applications requiring exceptional performance at very high temperatures, specialized heat-resistant stainless steels or nickel alloys may be more appropriate.
Heat Treatment
One of the major advantages of 17-4 PH is its ability to achieve high strength through precipitation hardening.
Solution Treatment
The material is generally solution treated at approximately 1025–1050°C, followed by rapid cooling.
Aging Treatment
After solution treatment, controlled aging is performed to achieve the required mechanical properties.
Common conditions include:
- H900 – Maximum strength and hardness
- H925 – High strength with improved toughness
- H1025 – Balanced strength and ductility
- H1075 – Improved toughness and strength balance
- H1150 – Higher toughness and ductility
The appropriate condition should be selected according to the required strength, hardness, toughness, and service environment.
Welding
Stainless Steel 17-4 PH has good weldability when appropriate procedures are followed.
Welding Processes
- GTAW / TIG
- GMAW / MIG
- SMAW
- SAW
- Laser Welding
Important Considerations
Heat treatment requirements before and after welding depend on the material condition and project requirements.
Post-weld heat treatment may be required to obtain the desired combination of mechanical properties.
Welding procedures should be qualified according to applicable standards and the required service conditions.
Fabrication
Machining
17-4 PH can be machined effectively in suitable heat-treatment conditions, particularly before final aging.
Common operations include:
- Turning
- Milling
- Drilling
- Grinding
- Threading
Forming
Forming is generally easier in the solution-treated condition than after precipitation hardening.
Cutting
- Laser cutting
- Plasma cutting
- Waterjet cutting
- Mechanical sawing
Surface Finishing
- Grinding
- Polishing
- Passivation
- Electropolishing
Applications
Aerospace Industry
- Structural components
- Aircraft components
- Landing gear components
- Engine components
- High-strength mechanical parts
Oil & Gas Industry
- Valve bodies
- Valve stems
- Pumps
- Mechanical components
- Control equipment
Petrochemical Industry
- Pump shafts
- Process equipment
- Mechanical components
- High-strength parts
Power Generation
- Turbine components
- Pump components
- Shafts
- Auxiliary equipment
Marine Industry
- Shafts
- Pumps
- Valves
- Mechanical components
Industrial Manufacturing
- Fasteners
- Gears
- Pins
- Shafts
- Machine components
- High-strength machined parts
Stainless Steel 17-4 PH in Tunisia, Algeria, Morocco & Libya
Stainless Steel 17-4 PH is suitable for industrial projects across Tunisia, Algeria, Morocco, and Libya where a combination of high mechanical strength, hardness, corrosion resistance, and dimensional stability is required.
It is particularly suitable for aerospace, oil & gas, petrochemical, power generation, marine, pump and valve manufacturing, and mechanical engineering.
The appropriate aging condition—H900, H925, H1025, H1075, or H1150—should be selected according to the required strength, hardness, toughness, ductility, and operating conditions.
17-4 PH vs 316L
| Property | 17-4 PH | 316L |
|---|---|---|
| Type | Martensitic precipitation-hardening | Austenitic |
| Mechanical Strength | Very High | Moderate |
| Hardness | Very High after aging | Moderate |
| Corrosion Resistance | Good | Excellent |
| Heat Treatment Hardening | Yes | No |
| Magnetic | Yes | Generally Non-Magnetic |
| Chloride Resistance | Moderate | Very Good |
| Main Advantage | High mechanical strength | Corrosion resistance |
| Typical Applications | High-strength components | Corrosive environments |
Conclusion
Stainless Steel 17-4 PH (UNS S17400 / EN 1.4542) is a precipitation-hardening stainless steel offering an excellent combination of very high mechanical strength, hardness, good corrosion resistance, fatigue resistance, and dimensional stability.
Its ability to achieve different mechanical properties through controlled aging treatments from H900 to H1150 makes it highly versatile for demanding engineering applications.
Available in sheets, plates, round bars, forgings, tubes, pipes, flanges, and machined components, Stainless Steel 17-4 PH is a reliable material for aerospace, oil & gas, petrochemical, power generation, marine, pump and valve, and mechanical engineering applications across Tunisia, Algeria, Morocco, Libya, and international markets.
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