17-7PH Alloy (UNS S17700)
- High strength and hardness.
- Great fatigue properties.
- Corrosion resistance.
- Less distortion upon heating.
- Low workability and ductility.
Description
Overview:
17-7PH stainless steel is one of those materials that exhibit different characteristics under different circumstances. It is semi austenitic when annealed and martensitic when it is in a hardened state. Thanks to this, you can easily form into the shape you want under annealed stated and have it hardened using heat treatment.
Normally the hardening process takes place using two components RH 9550 and TH1050. Because of this, 17-7PH shows characteristics according to the mater that got involved during the hardening process. This alloy is widely used in aerospace industry due to its good mechanical and physical properties.
Common Names:
- 17-7 PH Stainless Steel
- ATI 17-7
- UNS S17700
Executive Standards:
Tube, Pipe, Forging and Bar
- AMS 5568
- ASTM A182
- ASME SA182
- AMS 5644
- AMS 5678
Plate, Sheet, and Strip
- AMS 5528
- AMS 5529
- ASTM A693
Fittings
- ASTM A403
- ASME SA403
Others
- ASTM A313
- ASTM A564
- ASTM A579
- ASTM A70
Chemical Properties:
| Iron (%) | 70.59 |
| Chromium (%) | 16-18 |
| Nickle (%) | 6.50-7.75 |
| Aluminum (%) | 1.50 |
| Manganese (%) | Max 1.00 |
| Silicon (%) | Max 1.00 |
| Others (%) | Remainder |
Mechanical Properties:
| Yield Strength (MPa) | 276 |
| Yield Strength (psi) | 40,000 |
| Ultimate Tensile Strength (MPa) | 896 |
| Ultimate Tensile Strength (psi) | 130,000 |
| Modulus Of Elasticity (GPa) | 240 |
| Modulus Of Elasticity (ksi) | 29600 |
| Elongation | 35% |
| Hardness
(Rockwell C) |
38 |
Physical Properties:
| Density | lb/in3 | 0.282 |
| g/cm3 | 7.81 | |
| Melting Point | °F | 2560-2625 |
| °C | 1404-1440 | |
| Electrical Resistivity | μΩ-in | 21 |
| μΩ-cm | 80 | |
| Thermal Conductivity
(At 300°F) |
W/m-K | 16.87 |
| Btu/hr-ft²-in-°F | 117 | |
| Poisson’s Ratio | No unit | 0.27-0.30 |
Key Features:
Formability: You can easily form this material and get it to the chape you want it to be without any issues. But it hardens rapidly, so caution needs to be taking while using this material.
Corrosion resistance: You get a varied option in terms of corrosion resistance. Depending on the composition that you choose, the resistance of this material varies. So, you get a wide option to choose from.
Weldability: Though 17-7 stainless steel properties are not the best for welding in the group, it will be easy to work with if you follow the proper methods.
Product Forms Available:
- Pipe
- Tube
- Rod
- Bars
- Plate
- Sheet
- Strip
Applications:
- Surgical instruments
- Springs
- Aerospace components
- Blades
Possible Alternative Grades:
- 17-4PH Alloy: This grade shares most of its properties with 17-7PH, but the difference comes in the level of ferrite, which makes it a bit more magnetic.
Frequently Asked Questions:
- 17-7PH alloy falls in which category of precipitation hardening stainless steel?
17-7 PH is a semi-austenitic grade of precipitation hardening stainless steel.
- Is 17-7 PH stainless steel magnetic?
It is comparatively less magnetic to the other PH grades of stainless steel.
- What is the standard heat treatment for 17-7 PH stainless steel?
Heat treatment for 17-7 PH consists of three major processes.
- Austenitic conditioning
- Transformation (austenitic-martensitic)
- Precipitation hardening
