What is S17700 material?
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What is S17700 material?
S17700 material is 17-7 PH (precipitation hardening) stainless steel, a high-strength semi-austenitic alloy that is easily formed in the annealed condition. It possesses excellent mechanical properties, good corrosion resistance (similar to Type 304 stainless steel), and minimal distortion during heat treatment, making it ideal for aerospace components, springs, and other high-stress applications.
What is the UNs number for 631 stainless steel?
The UNS number for 631 stainless steel, also known as 17-7PH, is UNS S17700. This precipitation-hardening alloy offers high strength, good formability, and excellent spring properties, making it popular in aerospace and other demanding applications.
What is the composition of UNS S17700?
UNS S17700, also known as 17-7 PH stainless steel, is a precipitation-hardening alloy primarily composed of Chromium (16-18%), Nickel (6.5-7.75%), Aluminum (0.75-1.5%), and Iron (balance), with small amounts of Carbon (max 0.09%), Manganese (max 1.0%), Silicon (max 1.0%), Phosphorus (max 0.04%), and Sulfur (max 0.03%). Its distinctive combination of elements provides high strength, good corrosion resistance, and formability, making it popular for aerospace and springs.
17-7ph material physical Properties
| Properties | Metric | Imperial |
| Density | 7.80 g/cm³ | 0.282 lb./in³ |
17-7 ph stainless steel Mechanical Properties
| Properties | Metric | Imperial |
| Tensile Strength | 1170 MPa | 170000 ksi |
| Yield Strength | 965 MPa | 140000 ksi |
| Elastic Modulus | 204 GPa | 29600 ksi |
| Poisson's Ratio | 0.27 – 0.30 | 0.27 – 0.30 |
| Elongation at Break | 6% | 6% |
| Hardness, Rockwell B (converted from Brinell) | 38 | 38 |
17-7PH stainless steel Thermal Properties
| Properties | Metric | Imperial |
| Thermal Expansion (@ 0.000 – 100°C/32 – 212°F) | 11 µm/m°-C | 6.11 µin/in°F |
| Thermal Conductivity | 16.4 W/mK | 114 BTU in/hr.ft².°F |
UNS S17700 material Fabrication and Heat Treatment
UNS S17700 (17-7 PH) is a precipitation-hardening stainless steel offering high strength, good formability, and corrosion resistance, fabricated by forming in a soft austenitic state (Condition A) then hardening via low-temperature treatments (like RH950 or TH1050) to achieve specific mechanical properties, minimizing distortion compared to conventional steels, making it ideal for aerospace and springs.
UNS S17700 Applications
Key Applications by Industry:
Aerospace & Aviation: Aircraft structural parts, fasteners, springs, torsion bars, encapsulated bellows, diaphragms, jet engine parts, missile components.
Medical Devices: Surgical instruments, biopsy needles, clips, clamps, micro springs, cutting tools, punch tools.
Oil & Gas / Chemical Processing: Valve components, springs, fasteners, equipment requiring strength in corrosive environments.
General Engineering: Springs, washers, rings, clips, heat exchangers, antennas, measuring instruments, fluid seals, and general tooling.
What is the differences between UNS S17700 and UNS S17400?
UNS S17400 (17-4 PH) and UNS S17700 (17-7 PH) are both precipitation-hardening stainless steels, but S17700 has higher aluminum (Al) content, making it harder to weld and prone to slag formation, while S17400 offers better overall strength and corrosion resistance, often comparable to 304 stainless, making S17400 generally preferred for its balance of properties and weldability in demanding aerospace and industrial uses.
What is the differences between UNS S17700 and UNS S15500?
UNS S17700 (17-7 PH) and UNS S15500 (15-5 PH) are both precipitation-hardening stainless steels, but due to more precise compositional control and a more uniform microstructure, S15500 exhibits significantly better transverse ductility and toughness, especially in thicker sections, making it more suitable for critical aerospace components. S17700 (17-7 PH), on the other hand, is known for its high strength and good corrosion resistance, but is more prone to cracking in thicker components.
GNEE is a trusted supplier of precipitation-hardening stainless steel and specialty alloys in China. We supply 17-4 PH, 15-5 PH, and 17-7 PH alloys in various forms including bars, plates, profiles, and forgings. All products are sourced from certified steel mills and undergo rigorous chemical composition and mechanical property testing to ensure reliable quality.
Whether you are in the aerospace, oil and gas, marine engineering, or defense industry, we ensure that every batch of our products meets international standards and your specific application requirements.
Click here to view our complete range of precipitation-hardening alloys: PH Alloys.
