R30605 is a solid-solution-strengthened cobalt–chromium–tungsten–nickel alloy — the strongest of the fabricable cobalt-base alloys — combining excellent high-temperature strength with good oxidation resistance to about 980 °C (1800 °F) and outstanding resistance to sulfidation, wear and galling. This datasheet presents the material within the American (ASTM / SAE-AMS / UNS) standard system.
The cobalt base with 20% chromium provides oxidation and hot-corrosion resistance, while 15% tungsten gives solid-solution strengthening and 10% nickel improves fabricability and stability of the face-centred-cubic structure. The alloy is non-magnetic, retains useful strength to about 1000 °C, and resists metal galling and wear. It work-hardens very rapidly, so frequent intermediate annealing is recommended for complex forming. It is normally melted by vacuum induction melting followed by electroslag remelting (ESR).
Because of its long and widespread use it is an exceptionally well-characterised material. Typical applications include gas-turbine combustor and hot-section components, aerospace and industrial turbine hardware, and — at surgical-implant quality (ASTM F90) — orthopaedic and cardiovascular implants. It is supplied solution-heat-treated (2150–2250 °F, rapid quench); high strength can also be developed by cold work, in which condition it remains non-magnetic.
Values per manufacturer (Haynes / Ulbrich) data, solution-annealed condition.
| Property | Value | Unit |
|---|---|---|
| Density | 9.13 | g/cm³ |
| Melting range | 1330–1410 | °C |
| Young's modulus (20 °C) | 225 | GPa |
| Specific heat capacity (20 °C) | 385 | J/kg·K |
| Thermal conductivity (20 °C) | 9.4 | W/m·K |
| Electrical resistivity (20 °C) | 0.89 | µΩ·m |
| Coefficient of thermal expansion (25–100 °C) | 12.3 | µm/m·°C |
| Magnetic response | Non-magnetic (incl. cold-worked) | — |
| Maximum oxidation-resistance temperature | ~980–1095 | °C |
Limiting composition per AMS 5537 (UNS R30605).
| Element | Symbol | Min % | Max % | Role in Alloy |
|---|---|---|---|---|
| Cobalt | Co | Balance | — | Base element; high-temperature strength + wear/galling resistance |
| Chromium | Cr | 19.0 | 21.0 | Oxidation + sulfidation + hot-corrosion resistance |
| Tungsten | W | 14.0 | 16.0 | Solid-solution strengthening |
| Nickel | Ni | 9.0 | 11.0 | Fabricability; FCC structure stability |
| Manganese | Mn | 1.0 | 2.0 | Deoxidiser |
| Iron | Fe | — | 3.0 | Residual |
| Carbon | C | 0.05 | 0.15 | Carbide strengthening |
| Silicon | Si | — | 1.0 | Deoxidiser |
| Phosphorus | P | — | 0.03 | Residual impurity |
| Sulphur | S | — | 0.03 | Residual impurity |
Typical room-temperature properties, solution-annealed condition.
| Property | Value | Source |
|---|---|---|
| Ultimate tensile strength | ~1000 MPa | Solution-annealed (sheet/bar/plate) |
| 0.2% proof strength (yield) | ~475–505 MPa | Solution-annealed |
| Elongation at break | ~55–60 % | Solution-annealed |
| Hardness | ~240–280 HB | Solution-annealed |
The alloy work-hardens very rapidly and can be substantially strengthened by cold work, remaining non-magnetic in the cold-worked condition. It retains good strength to elevated temperatures. Values are typical; confirm against the mill test certificate for each delivery.
| Environment | Performance | Notes |
|---|---|---|
| High-temperature oxidation | Good | To ~980–1095 °C; Cr₂O₃ scale |
| Sulfidation | Outstanding | Key advantage of cobalt base |
| Wear / galling | Outstanding | Cobalt base resists metal galling |
| High-temperature strength | Excellent | Strongest fabricable cobalt alloy; useful to ~1000 °C |
| Hot corrosion | Very Good | Marine / combustion environments |
| Body-fluid corrosion (implant) | Excellent | ASTM F90 surgical-implant quality |
| Metallurgical stability | Caution | Loses room-temp ductility after long mid-temperature exposure (like other superalloys) |
A solid-solution cobalt-base alloy; strengthened by solid solution and carbides (and by cold work). Heat treatment is solution annealing.
Solution Anneal Temperature: 1177–1232 °C (2150–2250 °F), followed by rapid air or water quench Purpose: dissolves carbides, restores ductility and develops optimum properties.
Forming note: the alloy work-hardens very rapidly, so frequent intermediate solution anneals are recommended for complex or multi-stage forming. Hot working is carried out from ~1205 °C (2200 °F).
Readily welded by most conventional methods — gas-tungsten-arc (GTAW), gas-metal-arc (GMAW), shielded-metal-arc (SMAW), electron-beam and resistance welding. Welding behaviour is similar to Haynes 188. Submerged-arc welding is not recommended (high heat input and slow cooling promote cracking).
| Welding Process | Applicability | Filler / Consumable |
|---|---|---|
| GTAW / TIG · GMAW / MIG | Excellent | AMS 5796 matching wire (UNS W73605) |
| SMAW / stick | Good | AMS 5797 coated electrode |
| EB / resistance | Good | — |
Use matching-composition filler. Keep joints clean; avoid submerged-arc welding.
Machining Guidelines
| Parameter | Recommendation |
|---|---|
| Work hardening | Very rapid; rigid setup, sharp tooling, positive rake, low speeds |
| Intermediate anneal | Frequent solution anneals for complex forming |
| Coolant | Ample flood coolant |
Forming Processes
| Process | Notes |
|---|---|
| Hot working | From ~1205 °C (2200 °F) |
| Cold forming | Possible but work-hardens rapidly; intermediate anneals needed |
| Solution anneal | 1177–1232 °C, rapid quench, to restore ductility |
| Industry | Typical Components | Key Requirements |
|---|---|---|
| Gas turbines | Combustor liners, hot-section sheet components, rings | High-temp strength + oxidation/sulfidation resistance |
| Aerospace | Military and commercial turbine-engine hardware | Strength to ~1000 °C |
| Medical | Orthopaedic and cardiovascular implants (ASTM F90) | Biocompatibility; surgical-implant quality |
| Industrial | Wear/galling-resistant high-temperature parts | Wear + galling resistance |
| Power / process | High-temperature structural components | Sulfidation + thermal stability |
| Product Form | ASTM / AMS Standard | Notes |
|---|---|---|
| Sheet, strip and plate | AMS 5537 | Solution-annealed |
| Bar, rod and forging stock | AMS 5759 | Solution-annealed |
| Welding wire | AMS 5796 | Matching filler |
| Welding rod | AMS 5797 (UNS W73605) | Coated-electrode / rod filler |
| Bar and wire (surgical implant) | ASTM F90 | Surgical-implant quality |
| Welding consumables | AWS A5.21 (AWS 060) matching Co-Cr-W filler | — |
Cobalt-base high-temperature alloy. UNS R30605 (wrought); UNS W73605 (welding filler). Listed in NACE MR0175 / ISO 15156-3.
| UNS | Co/Ni | Cr % | Other | Best Used For |
|---|---|---|---|---|
| R30605 | Co bal | 19–21 | W 14–16, Ni 9–11 | Strongest fabricable Co alloy; turbine + implant |
| R30188 | Co bal | 20–24 | W 13–15, Ni 22 | Better oxidation to 1095°C; turbine |
| N06230 | Ni bal | 20–24 | W 14, Mo 2 | Ni-base; high-temp strength + stability |
| R30006 | Co bal | 27–32 | W 4–6 | Hardfacing; extreme wear (cast/weld) |
| N06625 | Ni bal | 20–23 | Mo 9, Nb | Ni-base; aqueous corrosion + strength |




