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Short Description:
17-7 PH is a precipitation-hardening stainless steel which combines high strength and hardness.
The alloy has excellent fatigue properties, good corrosion resistance and is easily formed. Due to the alloys good mechanical and physical properties, 17-7PH is particularly popular in the aerospace sector. The alloy can be used in the manufacture of flat springs up to 315°C (600°F).
Avliable Products: Wire, Pipe, Strip, Sheet, Plate, Flange,Bar
Product Description
17-7PH Precipitation Hardening Alloy is a semi-austenitic stainless steel which is austenitic in the annealed condition, but martensitic in the hardened condition. 17-7PH provides high strength and hardness, excellent fatigue properties, good corrosion resistance and minimum distortion upon heat treatment. It is easily formed in the annealed condition, then hardened to high strength levels by simple heat treatments to Conditions RH 950 and TH 1050. The exceptionally high strength of Condition CH 900 offers many advantages where limited ductility and workability are permissible. In its heat treated condition, this alloy provides exceptional mechanical properties at temperatures up to 900 °F (482 °C).
Chemical Composition
| % | Cr | Ni | Mn | Si | Al | C | P | S | Fe |
|---|---|---|---|---|---|---|---|---|---|
| Min | 16 | 6.5 | - | 1 max | 0.75 | - | - | - | - |
| Max | 18 | 7.75 | 1 | 1 | 1.5 | 0.09 | 0.04 | 0.03 | Balance |
Physical Properties
| Properties | Metric | Imperial |
|---|---|---|
| Density | 7.80 g/cm3 | 0.282 lb/in3 |
Mechanical Properties
| Properties | Tensile strength | Yield strength | Modulus of elasticity | Poisson’s ratio | Elongation at break | Hardness, Rockwell C |
|---|---|---|---|---|---|---|
| Metric | 1170 MPa | 965 MPa | 204 GPa | 0.27-0.30 | 6% | 38 |
| Imperial | 170000 psi | 140000 psi | 29600 ksi | 0.27-0.30 | 6% | 38 |
Fabrication and Heat Treatment
Machinability
Machinability of stainless steel grade 17-7 PH is rated at 75 % of B1112. On machining, this alloy displays long gummy chips and requires chip breakers. It is recommended that slow speeds and constant feeds while machining will provide excellent results.
Heat Treatment
For heat treating stainless steel grade 17-7 PH, three important steps need to be carried out – austenite conditioning, cooling to transform the austenite to martensite, and precipitation hardening to condition TH 1050 or RH 950.
Forming
Forming characteristics of stainless steel grade 17-7 PH are similar to stainless steel grade 301. For radical forming operations, intermediate annealing may be required.
Welding
Common arc and resistance methods can be used with stainless steel grade 17-7 PH. It is recommended that during fusion welding inert gas shielding should be performed to reduce the oxidation of aluminum during the process.
Annealing
Annealing of stainless steel grade 17-7 PH is performed at 1066°C (1950°F) for 3 min for every 0.1 inch (2.5 mm) of thickness, and then air cooled.
Aging
Stainless steel grade 17-7 PH is solution annealed at 1177°C (2150°F) for 4 h and air cooled. Same step is performed at 1079°C (1975°F) for 4h and air cooled, then at 843°C (1550°F) for 24h and air cooled, and at 760°C (1400°F) for 16h and air cooled. This completed the precipitation hardening process. For excellent results and performance, the material should be clean and free from scale and impurities.
- Bars & Rods
- sheet & plate
- strip & coil
- welding wire &Spring wire
- Seamless tube & Welded pipe
» Round Bar & Square Bar & Hexagon Bar
Diameter : φ8～φ300mm
Length:10mm-6000mm
Hot forging,Hot Rolling,Cold Rolling
Bright Surface, Polished Surface, Black Surface
» Tube & Pipe:Seamless Pipe & Welding Pipe
Cold Drawing Seamless Pipe φ10～φ220mm
Hot Extrusion pipe:φ50～φ250mm
Others :U Blend Tube and Elbow
» Hot Rolled & Cold Rolled Plate Sheet
Thickness≦2.0mm Width:≦1500m
Thickness≧4.0mm Width:≦2500m
Length Within 6500mm
» Strip & Tape Ribbon
Thickness≧:0.01mm
Width：15mm-300mm
Cold rolling BA Strip, Hard & Soft Condition
» Straight Length Wire & Spool Wire
Welding Wire:ɸ0.1mm～6.0mm
Cut length Wire:φ1.0～φ8.0mm
Package:5-25kg/Spool
17-7 PH Applications
- Tooling in the Aerospace Industry
- CNC components
- Mould & gauge making
- General tooling
- Bulkheads
- Retaining rings
- Springs