17-7PH Stainless Steel
17-7PH is an austenitic martensitic precipitation hardening stainless steel developed from 18-8CrNi with an aluminum addition. It contains 16% to 18% chromium, 6.5% to 7.75% nickel, and 0.75% to 1.5% aluminum. Solution treatment produces an unstable austenitic structure that transforms during aging into low carbon tempered martensite. The source lists high strength, hardness of HRC 38 to 46, corrosion resistance above ordinary martensitic stainless steel, and fatigue resistance. Heat treatment can adjust properties for service at ≤427℃.
Product details
Chemical composition
| 17-7PH | C | Si | Mn | P | S | Ni | Cr | Al |
|---|---|---|---|---|---|---|---|---|
| min | – | – | – | – | – | 6.5 | 16.0 | 0.75 |
| max | 0.09 | 1.0 | 1.0 | 0.04 | 0.03 | 7.7 | 18.0 | 1.5 |
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Grade equivalents
| English Item | UNS | W.Nr. | JIS | GB/T | Other Grades |
|---|---|---|---|---|---|
| 631 17-7PH | S17700 | 1.4568 | SUS631 | 07Cr17Ni7Al 0Cr17Ni7Al | X7CrNiAl17-7 |
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Physical properties
| Density g/cm³ | 7.85 |
|---|---|
| Melting range ℃ | 1390-1430 |
| Thermal conductivity (100℃) λ/(W/m•℃) | 16.3 |
| Specific heat J/kg•℃ | 460.6 |
| Elastic modulus GPa | 200 |
| Electrical resistivity μΩ•m | 0.8 |
| Linear expansion coefficient a/10-6℃-1 | 15.3 |
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Mechanical properties
| Tensile strength Rm N/mm | ≥1140 |
|---|---|
| Yield strength RP0.2 N/mm | ≥960 |
| Elongation % | ≥5 |
| Hardness HB | ≥363 |
| *After aging heat treatment | |
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Applications
- Aerospace: aircraft structures, engine components such as thrust reversers and compressor discs, and satellite components
- Medical devices: surgical instruments, orthopaedic implants such as artificial joints, and dental instruments
- Chemical equipment: corrosion-resistant piping, valves, reactors, and heat exchangers handling acids and chlorides
- Energy: oil-drilling equipment and sulfur-corrosion-resistant refinery components
- Precision machinery: high-strength springs such as bellows and resilient elements, sensors, and fasteners
- Marine engineering: marine shafts and seawater-corrosion-resistant structures
- Environmental equipment: high-temperature waste-incinerator components and corrosion-resistant wastewater-treatment systems
Available product forms
- Round Bar
- Wire
- Forgings
- Plate
- Strip
- Seamless Pipe
- Welded Pipe
- Capillary Tube
- Flanges
- Pipe Fittings
- Non-standard Custom Parts
Values follow the Milike materials catalogue and are provided for preliminary review. Confirm the applicable purchase specification, heat treatment condition, and inspection requirements before final material selection.
- Heat and batch traceability
- PMI testing available
- Cut-to-size processing
- Material certificates on request
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