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
Alloy N-155 is an iron–nickel–chromium–cobalt-base multi-element high-temperature alloy (with molybdenum, tungsten, niobium and nitrogen additions), recommended for high-stress service to about 815 °C (1500 °F) and moderate-stress service to about 1095 °C (2000 °F). This datasheet presents the material within the American (SAE-AMS / UNS) standard system.
Its high-temperature strength is inherent and is not dependent on age-hardening — the properties are developed in the solution-heat-treated condition. The balanced Cr-Ni-Co matrix with Mo and W solid-solution strengthening, plus niobium and nitrogen, provides a combination of high-temperature strength, excellent oxidation resistance and good ductility. Production and use of the alloy date back to the late 1940s. It also has good resistance to corrosion in certain oxidising and reducing media: when solution-treated it has about the same nitric-acid resistance as stainless steel, better resistance than stainless to weak hydrochloric acid, and withstands all concentrations of sulphuric acid at room temperature.
It is readily fabricated — machined, forged and cold-formed by conventional methods — and welded by various arc and resistance processes. It is available as sheet, strip, plate, wire, coated electrodes, billet and castings. Typical applications include aircraft tailpipes and tail cones, afterburner parts, exhaust manifolds, combustion chambers, turbine blades, buckets and nozzles, high-temperature bolts, and heat-treating equipment.
Values per manufacturer (Haynes) data, solution-annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 8.23 | g/cm³ |
| Melting range | 1338–1380 | °C |
| Young's modulus (20 °C) | 213 | GPa |
| Specific heat capacity (20 °C) | 431 | J/kg·K |
| Thermal conductivity (20 °C) | 12.0 | W/m·K |
| Electrical resistivity (20 °C) | 0.91 | µΩ·m |
| Coefficient of thermal expansion (20–100 °C) | 14.8 | µm/m·°C |
| High-stress service temperature | ~815 (1500 °F) | °C |
| Moderate-stress service temperature | ~1095 (2000 °F) | °C |
Limiting composition per AMS 5532 (UNS R30155).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Iron | Fe | Balance | — | Base element |
| Chromium | Cr | 20.0 | 22.5 | Oxidation + corrosion resistance |
| Nickel | Ni | 19.0 | 21.0 | Austenitic-matrix stability |
| Cobalt | Co | 18.5 | 21.0 | High-temperature strength |
| Molybdenum | Mo | 2.5 | 3.5 | Solid-solution strengthening |
| Tungsten | W | 2.0 | 3.0 | Solid-solution strengthening |
| Manganese | Mn | 1.0 | 2.0 | Deoxidiser |
| Niobium | Nb | 0.75 | 1.25 | Carbide/strengthening |
| Nitrogen | N | 0.10 | 0.20 | Solid-solution strengthening |
| Carbon | C | 0.08 | 0.16 | Carbide formation |
| Silicon | Si | — | 1.0 | Deoxidiser |
| Phosphorus | P | — | 0.040 | Residual impurity |
| Sulphur | S | — | 0.030 | Residual impurity |
Note: an iron-base multi-element alloy (Fe-Cr-Ni-Co + Mo/W/Nb/N); strength is inherent in the solution-treated condition, not age-hardening-dependent.
Typical room-temperature properties, solution-annealed condition.
| Property | Value | Source |
|---|---|---|
| Ultimate tensile strength | ~815–960 MPa | Solution-annealed |
| 0.2% proof strength (yield) | ~380–470 MPa | Solution-annealed |
| Elongation at break | ~40–48 % | Solution-annealed |
| Hardness | ~80–95 HRB | Solution-annealed |
High-temperature strength is inherent in the solution-treated condition and is not developed by age-hardening. The alloy retains useful strength to high temperatures and has good ductility. Values are typical; confirm against the mill test certificate for each delivery.
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation | Excellent | To ~1095 °C (2000 °F) |
| Nitric acid (solution-treated) | Good | About the same as stainless steel |
| Hydrochloric acid (weak) | Good | Better than stainless steel |
| Sulphuric acid (room temp) | Good | Withstands all concentrations at RT |
| High-temperature strength | Excellent | High stress to 815 °C; moderate to 1095 °C |
| Reducing + oxidising media | Good | Resistance in certain media both conditions |
An iron-base solid-solution alloy; high-temperature strength is inherent and not developed by age-hardening. Heat treatment is solution annealing.
Solution Anneal Temperature: ~1177 °C (2150 °F), followed by rapid cooling Purpose: dissolves carbides, develops the inherent high-temperature properties and restores ductility.
The alloy does not rely on precipitation/age-hardening; its strength is obtained in the solution-treated condition. Hot working is carried out at elevated temperature followed by solution annealing.
Readily welded by various arc and resistance-welding processes, and readily machined, forged and cold-formed by conventional methods.
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG · GMAW / MIG | Excellent | AMS 5794 matching wire (N-155 type) |
| SMAW / stick | Good | AMS 5795 coated electrode |
| Resistance welding | Good | — |
Use matching-composition filler. Keep joints clean. The alloy's good fabricability makes it well suited to welded high-temperature sheet assemblies.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Work hardening | Moderate-to-high; rigid setup, sharp tooling, positive rake |
| Cutting | Low-to-moderate speed, ample feed; flood coolant |
| Preferred condition | Solution-annealed |
Forming Processes
| Process | Notes |
|---|---|
| Hot forming | Conventional hot working; solution anneal afterwards |
| Cold forming | Readily cold-formed by conventional methods |
| Solution anneal | ~1177 °C after forming, rapid cool |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Aerospace | Tailpipes, tail cones, afterburner parts, exhaust manifolds | Oxidation + strength to 1095 °C |
| Gas turbines | Combustion chambers, turbine blades, buckets, nozzles | High-temperature strength |
| Aerospace structures | Shafts, rotors | Strength + fabricability |
| Fasteners | High-temperature bolts | Strength at temperature |
| Industrial | Heat-treating equipment | Economical high-temperature strength |
| Product Form | AMS Standard | Notes |
|---|---|---|
| Sheet, strip and plate | AMS 5532 | Solution-annealed |
| Bars, rings and forgings | AMS 5769 | Solution-annealed |
| Welding wire | AMS 5794 | Matching filler |
| Coated electrodes | AMS 5795 | Matching electrode |
| Castings | Sand / investment | Per manufacturer |
Iron-base multi-element high-temperature alloy. UNS R30155 (wrought); UNS W73155 (welding filler). AISI 661 / SAE 661.
| Alloy | Base | Cr % | Other | Best Used For |
|---|---|---|---|---|
| Alloy N-155 | Fe bal | 20–22.5 | Co 19, Mo/W/Nb/N | Iron-base; inherent strength to 1095°C |
| A-286 | Fe bal | 13.5–16 | Ti+Al age-hard. | Iron-base age-hardened; to 704°C |
| Alloy 25 / L605 | Co bal | 19–21 | W 15, Ni 10 | Cobalt-base; strongest fabricable Co alloy |
| Alloy X | Ni bal | 20.5–23 | Mo 9, Fe 18 | Ni-base; combustor; oxidation to 1200°C |
| Type 321 | Fe bal | 17–19 | Ti-stabilised | Stainless; lower temperature/cost |
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