Bar and Rod
Plate and Sheet
Strip
Pipe and Tube
Wire
Welding
Powder Material
Cast Products
Forged Products
Fittings
Fastening
Round Bar:
φ2–500 mm, 1–6 m length
Flat/Square Bar:
4–100 mm thickness/width
Hex Bar:
A/F 3–100 mm
Hollow Bar:
OD 20–300 mm
Sheet:
0.3–6 mm thickness
Medium Plate:
6–25 mm thickness
Heavy Plate:
25–100 mm thickness
Standard Strip:
0.05–3 mm thick,
10–600 mm wide
Precision strip:
0.01–0.5 mm thick,
tight tolerance ±0.005 mm
Foil:
0.005–0.1 mm thick
Seamless Tube:
OD 6–450 mm,
WT 1–50 mm,
1–12 m length
Welded Tube:
OD 10–600 mm,
WT 1–20 mm
Capillary Tube:
OD 1–10 mm,
WT 0.1–2 mm
Wire Form:
Cold Drawn Wire,
Bright Wire,
Spring Wire,
Fine Wire,
Ultra-fine Wire
General Diameter:
φ0.1–10 mm
Coil Weight:
50–500 kg,
customizable tolerance
Solid Wire:
φ0.8–4.0 mm
Flux-cored Wire:
φ1.2–4.0 mm
Welding Rod:
φ2.0–5.0 mm
Powder Form:
AM 3D Printing Powder,
Spherical Powder,
Gas-atomized Powder,
Water-atomized Powder
Particle Size:
10–150 μm
Sphericity:
≥90% for AM grade
Cast Ingot:
φ200–800 mm
Precision Casting:
min wall 0.5 mm
Cast Pipe:
OD 100–600 mm,
WT 10–50 mm
Forged Bar:
Φ35–500 mm
Forged Ring:
OD 200–2000 mm
Forging Weight:
1–5000 kg
Fittings Form:
Elbow, Tee, Reducer, Flange, Cap, Outlet, Lap Joint
Size range:
1/2''–24'' (DN15–DN600)
Wall thickness:
Sch10–Sch160, STD, XS, XXS
Pressure Class:
150–2500 LB
Fastening Form:
Bolt, Nut, Screw, Stud, Washer, Pin, Rivet
Metric: M3–M64
Imperial: #4–2.5''
Length: 6–500 mm
17-7PH is a chromium-nickel-aluminium semi-austenitic precipitation-hardening (PH) stainless steel. This datasheet presents the material within the American (ASTM / ASME / AMS / UNS) standard system.
With about 17% chromium, 7% nickel and 1% aluminium, 17-7PH is the most formable of the PH grades and reaches very high strength and hardness after heat treatment. It is supplied in the soft austenitic (Condition A) state, formed, then transformed to martensite and precipitation-hardened by a multi-step heat treatment that precipitates an aluminium-rich phase. It is less magnetic than the martensitic PH grades, distorts little on hardening, and retains useful properties to about 425 °C. It provides excellent spring characteristics and fatigue resistance.
Typical applications include springs, diaphragms, bellows, retaining rings, fasteners and aerospace structural and instrument components requiring high strength with good formability.
Typical values, TH1050 condition.
| Property | Value | Unit |
|---|---|---|
| Density | 7.81 | g/cm³ |
| Melting range | 1400–1440 | °C |
| Elastic modulus | 204 | GPa |
| Coefficient of thermal expansion (20–100 °C) | 11.0 | µm/m·°C |
| Thermal conductivity (20 °C) | 16.4 | W/m·K |
| Specific heat (20 °C) | 460 | J/kg·K |
| Structure | Semi-austenitic (precipitation-hardening) | — |
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 16.0 | 18.0 | Corrosion resistance |
| Nickel | Ni | 6.50 | 7.75 | Austenite stability |
| Aluminium | Al | 0.75 | 1.50 | Precipitation-hardening phase (Ni-Al) |
| Manganese | Mn | — | 1.00 | Deoxidiser |
| Silicon | Si | — | 1.00 | Deoxidiser |
| Carbon | C | — | 0.09 | Strength |
| Phosphorus | P | — | 0.040 | Residual impurity |
| Sulphur | S | — | 0.030 | Residual impurity |
Typical values by heat-treatment condition, per ASTM A564 / AMS 5528 for UNS S17700.
| Condition | Tensile strength | 0.2% Yield | Hardness |
|---|---|---|---|
| TH1050 | ≥1170 MPa (170 ksi) | ≥1030 MPa (150 ksi) | ~38 HRC |
| RH950 | ≥1380 MPa (200 ksi) | ≥1210 MPa (175 ksi) | ~43 HRC |
| CH900 (cold-rolled + aged) | ≥1655 MPa (240 ksi) | ≥1585 MPa (230 ksi) | ~46 HRC |
| Condition A (annealed) | ~895 MPa (130 ksi) | ~275 MPa (40 ksi) | ~B85 HRB |
Confirm against the mill test report. Elongation typically ≥1–6% in hardened conditions, higher in Condition A.
| Environment | Performance | Notes |
|---|---|---|
| Atmospheric / general | Good | Better than martensitic 400-series; below 304 |
| Mild acids | Moderate | At low concentrations |
| Chloride pitting | Moderate | Lower than austenitic grades |
| Oxidation | Good | To approximately 760 °C intermittently |
| Seawater | Limited | Not recommended for prolonged exposure |
Corrosion resistance is moderate — better than the martensitic PH and 400-series grades but below the austenitic stainless steels.
A semi-austenitic precipitation-hardening alloy; supplied in Condition A (soft, austenitic) and hardened by a multi-step transformation-plus-ageing sequence.
Solution Treatment (Condition A) Supplied solution-treated (~1065 °C) in the soft austenitic condition for forming.
Transformation and Precipitation Hardening TH1050: austenite-conditioning at ~760 °C, cool to transform to martensite, then age at ~565 °C. RH950: condition at ~955 °C, sub-zero cool (~−73 °C) to transform, then age at ~510 °C for higher strength. CH900: cold-roll to martensite then age at ~480 °C for maximum strength. Air cool after ageing.
Weldable by common fusion and resistance methods; matching filler is used. Heat treatment after welding develops full properties.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG | Good | Matching 17-7-type filler |
| GMAW / MIG | Good | Matching filler |
| Resistance / spot | Good | — |
Weld in Condition A; heat-treat after welding to develop strength.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Preferred condition | Condition A for best formability and machinability |
| Work hardening | High rate; positive feeds, rigid setup |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Cold forming | Excellent in Condition A (most formable PH grade) |
| Hot forming | ~1150–950 °C; solution treat + age afterward |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aerospace | Springs, retaining rings, structural parts | High strength + formability |
| Spring / fastener | Springs, washers, clips | Spring properties + fatigue resistance |
| Instrumentation | Diaphragms, bellows | Formability + fatigue resistance |
| General industrial | High-strength formed components | Strength + minimal distortion |
| Product Form | ASTM Standard | ASME / AMS |
|---|---|---|
| Plate, sheet and strip | ASTM A693 grade 631 | ASME SA-693 / AMS 5528 |
| Bar and wire | ASTM A564 grade 631 | ASME SA-564 / AMS 5529 / 5644 |
| Wire (spring) | ASTM A313 (631) | AMS 5678 |
| Welding consumables | Matching 17-7-type filler | — |
Chromium-nickel-aluminium semi-austenitic precipitation-hardening stainless steel. UNS S17700.
| Grade | Cr % | Ni % | Al % | Other | Best Used For |
|---|---|---|---|---|---|
| 17-7PH | 16–18 | 6.5–7.75 | 0.75–1.5 | — | Semi-austenitic PH; springs, formability |
| PH15-7Mo | 14–16 | 6.5–7.75 | 0.75–1.5 | Mo | Semi-austenitic PH; higher strength |
| AM-350 | 16–17 | 4–5 | — | Mo, N | Semi-austenitic PH; high strength |
| 17-4PH | 15–17.5 | 3–5 | — | Cu, Nb | Martensitic PH; general high strength |
| Type 301 | 16–18 | 6–8 | — | — | Work-hardening austenitic; springs |
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