Overview
SS17-4PH (AISI 630 / 17-4 PH Stainless Steel) is a precipitation-hardening martensitic stainless steel that combines high strength, excellent corrosion resistance, outstanding toughness, and superior heat treatment capability.
The designation 17-4PH refers to its approximate composition of 17% Chromium (Cr) and 4% Nickel (Ni), with additions of Copper (Cu) and Niobium (Nb/Cb) to achieve precipitation hardening.
SS17-4PH is one of the most widely used high-strength stainless steels in aerospace, medical, oil & gas, marine, semiconductor, defense, and precision engineering industries.
Compared with SS304 and SS316, 17-4PH offers dramatically higher strength while maintaining good corrosion resistance. Compared with Duplex 2205, it offers superior hardness and machinability but lower chloride resistance.
Material Specification
| Property | Value |
|---|---|
| Material Designation | 17-4 PH Stainless Steel |
| AISI Grade | 630 |
| UNS Number | S17400 |
| EN Grade | 1.4542 |
| Material Family | Precipitation Hardening Stainless Steel |
| Density | 7.75 g/cm³ |
| Magnetic Property | Magnetic |
| Standard Forms | Plate, Sheet, Bar, Rod, Forgings, Tubing |
Chemical Composition
| Element | Content (%) |
|---|---|
| Iron (Fe) | Balance |
| 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 |
| Carbon (C) | ≤0.07 |
| Manganese (Mn) | ≤1.00 |
| Silicon (Si) | ≤1.00 |
| Phosphorus (P) | ≤0.040 |
| Sulfur (S) | ≤0.030 |
Mechanical Properties
Condition A (Solution Annealed)
| Property | Value |
|---|---|
| Tensile Strength | 930–1070 MPa |
| Yield Strength | 725 MPa |
| Elongation | 16% |
| Hardness | 28–32 HRC |
H900 Condition
| Property | Value |
|---|---|
| Tensile Strength | 1310 MPa |
| Yield Strength | 1170 MPa |
| Hardness | 40–44 HRC |
| Elongation | 10% |
H1025 Condition
| Property | Value |
|---|---|
| Tensile Strength | 1170 MPa |
| Yield Strength | 1070 MPa |
| Hardness | 35–38 HRC |
| Elongation | 12% |
H1150 Condition
| Property | Value |
|---|---|
| Tensile Strength | 1035 MPa |
| Yield Strength | 860 MPa |
| Hardness | 28–32 HRC |
| Elongation | 16% |
Physical Properties
| Property | Value |
|---|---|
| Density | 7.75 g/cm³ |
| Melting Point | 1404–1440°C |
| Thermal Conductivity | 18.3 W/m·K |
| Electrical Resistivity | 0.80 μΩ·m |
| Thermal Expansion Coefficient | 10.8 × 10⁻⁶/K |
| Elastic Modulus | 196 GPa |
| Specific Heat Capacity | 460 J/kg·K |
Corrosion Resistance
Corrosion Performance
| Environment | Performance |
|---|---|
| Atmospheric Exposure | Excellent |
| Industrial Environment | Excellent |
| Fresh Water | Excellent |
| Mild Chemical Environment | Excellent |
| Marine Atmosphere | Good |
| Seawater Immersion | Moderate |
| Chloride Environment | Moderate |
17-4PH offers corrosion resistance similar to:
- SS304
- SS431
- Better than SS410
- Better than SS420
However, it does not match:
- SS316L
- Duplex 2205
- Super Duplex 2507
for chloride-rich environments.
Heat Treatment Conditions
Solution Annealing
| Process | Temperature |
|---|---|
| Solution Treatment | 1020–1060°C |
| Cooling | Air Cool |
Aging Treatments
| Condition | Aging Temperature |
|---|---|
| H900 | 482°C |
| H925 | 496°C |
| H1025 | 552°C |
| H1075 | 579°C |
| H1150 | 621°C |
Different aging temperatures allow optimization between strength and toughness.
International Equivalent Grades
| Standard | Equivalent Grade |
|---|---|
| ASTM / AISI | 630 |
| UNS | S17400 |
| EN | 1.4542 |
| DIN | X5CrNiCuNb16-4 |
| AMS | AMS 5643 |
| GB/T (China) | 05Cr17Ni4Cu4Nb |
| JIS | SUS630 |
| ISO | X5CrNiCuNb16-4 |
Available Forms
| Product Type | Availability |
|---|---|
| Plate | Yes |
| Sheet | Yes |
| Round Bar | Yes |
| Flat Bar | Yes |
| Forgings | Yes |
| Tubing | Yes |
| Wire | Yes |
| CNC Machining Stock | Yes |
Typical Applications
Aerospace Industry
- Aircraft Structural Components
- Landing Gear Parts
- Engine Components
- Fasteners
- Actuator Systems
Medical Industry
- Surgical Instruments
- Orthopedic Tools
- Medical Equipment Components
- Dental Equipment
Oil & Gas Industry
- Valve Components
- Pump Shafts
- Wellhead Equipment
- Downhole Tools
Semiconductor Industry
- Vacuum Equipment
- Precision Fixtures
- Process Components
Defense Industry
- Fire Control Systems
- Missile Components
- Precision Mechanical Parts
Marine Industry
- Propeller Shafts
- Marine Fasteners
- Pump Components
Manufacturing Characteristics
| Manufacturing Process | Rating |
|---|---|
| CNC Turning | Excellent |
| CNC Milling | Excellent |
| 5-Axis Machining | Excellent |
| Precision Grinding | Excellent |
| EDM Machining | Excellent |
| Heat Treatment | Outstanding |
| TIG Welding | Good |
| MIG Welding | Good |
| Laser Cutting | Excellent |
| Polishing | Excellent |
Advantages
Extremely High Strength
Much stronger than SS304 and SS316.
Excellent Corrosion Resistance
Suitable for many industrial environments.
Heat Treatable
Mechanical properties can be tailored.
Excellent Dimensional Stability
Ideal for precision components.
Good Machinability
Better than many high-strength alloys.
Aerospace Approved
Widely used in aerospace and defense industries.
Limitations
Lower Chloride Resistance Than SS316
Not ideal for seawater immersion.
Magnetic Material
Not suitable where non-magnetic performance is required.
Welding Requires Care
Post-weld heat treatment may be required.
More Expensive Than SS304
Higher alloying content increases cost.
Comparison with Other Stainless Steels
| Property | 17-4PH | SS316L | SS304 | Duplex 2205 | SS420 |
|---|---|---|---|---|---|
| Strength | Outstanding | Medium | Medium | High | High |
| Hardness | High | Low | Low | Medium | High |
| Corrosion Resistance | Excellent | Outstanding | Excellent | Outstanding | Moderate |
| Heat Treatable | Yes | No | No | No | Yes |
| Machinability | Good | Good | Good | Moderate | Good |
| Magnetic | Yes | No | No | Slightly | Yes |
Comparison with High-Performance Materials
| Material | Yield Strength (MPa) | Corrosion Resistance |
|---|---|---|
| 17-4PH H900 | 1170 | Excellent |
| SS316L | 170 | Outstanding |
| Duplex 2205 | 450 | Outstanding |
| Titanium Grade 5 | 880 | Outstanding |
| Inconel 718 | 1030 | Exceptional |
Available Surface Finishes
Mill Finishes
- Hot Rolled Finish
- Cold Finished Finish
- Ground Finish
- Bright Finish
Decorative Finishes
- Satin Finish
- Brushed Finish
- Hairline Finish
- Mirror Polish
Functional Finishes
- Passivation
- Electropolishing
- Glass Bead Blasting
- Shot Peening
- DLC Coating
- PVD Coating
- Hard Chrome Plating
Frequently Asked Questions (FAQ)
What is 17-4PH stainless steel?
17-4PH is a precipitation-hardening stainless steel that combines high strength, corrosion resistance, and excellent heat-treatment response.
What is 17-4PH used for?
Typical applications include:
- Aerospace Components
- Medical Equipment
- Oil & Gas Equipment
- Precision Machinery
- Defense Components
- Semiconductor Equipment
Is 17-4PH stronger than SS316?
Yes.
| Property | 17-4PH H900 | SS316L |
|---|---|---|
| Yield Strength | 1170 MPa | 170 MPa |
| Tensile Strength | 1310 MPa | 485 MPa |
17-4PH is approximately 6–7 times stronger in yield strength.
Is 17-4PH magnetic?
Yes. Unlike SS304 and SS316, 17-4PH is magnetic.
Can 17-4PH be heat treated?
Yes. It is specifically designed for precipitation hardening and can be supplied in multiple aged conditions.
What is the difference between 17-4PH and SS316L?
| Property | 17-4PH | SS316L |
|---|---|---|
| Strength | Much Higher | Lower |
| Corrosion Resistance | Excellent | Better |
| Heat Treatable | Yes | No |
| Magnetic | Yes | No |
Is 17-4PH suitable for aerospace applications?
Yes. It is one of the most widely used aerospace stainless steels due to its high strength-to-weight ratio.
Why is 17-4PH popular for CNC machining?
Because it combines:
- High Strength
- Good Machinability
- Dimensional Stability
- Corrosion Resistance
making it ideal for precision engineering.
Does GCNOV provide custom manufacturing services for 17-4PH?
Yes. GCNOV provides:
- CNC Machining
- 5-Axis Machining
- Precision Grinding
- Heat Treatment
- Aerospace Component Manufacturing
- Medical Device Components
- Oil & Gas Equipment Parts
- Surface Finishing
- Prototype Development
- Low-Volume Production
- Mass Production