17-7 PH
Material Data Sheet
17-7 PH is a chromium-nickel-aluminum precipitation hardening stainless steel that provides high strength and hardness and a moderate level of corrosion resistance up to 600˚F. This grade can be easily formed in the austenitic condition similar to Type 301 stainless steel and hardened to high strength levels using relatively low heat treatments that minimize distortion. The corrosion resistance of 17-7 PH is comparable to that of Type 304 stainless steel, especially in the CH 900 temper, and it has been used for spring applications, washers, eyelets, fittings, and fasteners.
Heat treatments can strengthen this type of stainless steel. The typical process for 17-7 PH heat treatment has three or four steps:
- Conditioning using austenite.
- Cooling, which turns the austenite into martensite.
- Precipitation hardening until Condition TH 1050 or RH 950 has been reached.
- To achieve the highest mechanical properties Condition A material is transformed to martensite at the mill by cold reduction to Condition C. After fabrication by the user, a single low-temperature heat treatment is preformed to achieve condition CH 900
| Element | Content (%) |
|---|---|
| Iron, Fe | 70.59 – 76.75 |
| Chromium, Cr | 16.0 – 18. |
| Nickel, Ni | 6.5 – 7.75 |
| Manganese, Mn | ≤ 1.0 |
| Silicon, Si | ≤ 1.0 |
| Aluminum, Al | 0.75 – 1.50 |
| Carbon, C | ≤ 0.09 |
| Phosphorous, P | ≤ 0.04 |
| Sulfur, S | ≤ 0.03 |
| Properties | Metric | English |
|---|---|---|
| Density | 7.80 g/cm3 | 0.282 lb/in3 |
| Melting Point | 1404 – 1440°C | 2560 – 2625°F |
| Properties | Metric | English |
|---|---|---|
| Hardness, Rockwell C | 43 | 43 |
| Tensile Strength, Ultimate | 1517 MPa | 220000 psi |
| Tensile Strength, Yield | 1310 MPa | 190000 psi |
| Elongation at Break | 5.0 % | 5.0 % |
| Modulus of Elasticity | 200 GPa | 29000 ksi |
| Poisson’s Ratio | 0.27 – 0.30 | 0.27 – 0.30 |
Stainless Steel 17-7 PH is used in the following application areas:
- Springs and washers
- Chemical processing equipment
- Heat exchangers
- Power boilers
- Superheater tubes
