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Haynes 25 (traditionally called L-605, UNS R30605 / W.Nr. 2.4964 / China GH5605) is a solid-solution strengthened cobalt-chromium-nickel-tungsten superalloy developed in the 1940s–50s by the Haynes Stellite Division (now Haynes International). It was the first commercially successful wrought cobalt-base superalloy designed for high-temperature strength (to ~980–1040°C / 1800–1900°F), sulfidation resistance, and good ductility in both room-temperature and cryogenic conditions.
Unlike precipitation-hardenable Ni-base alloys (Inconel 718, René 41), Haynes 25 derives strength only from W and Cr solid-solution hardening plus minor M₂₃C₆ / M₆C grain-boundary carbides. It cannot be age-hardened. Its key differentiator vs. the later Haynes 188 (UNS R30188) is the lower Ni content (~10% vs. ~22%), absence of rare-earth (La/Ce) additions, and correspondingly lower resistance to oxide-scale spallation under thermal cycling—but it is often the specified alloy for legacy aircraft-engine drawings, high-temperature springs, and biomedical implants.
1. UNS, Trade Names & International Equivalents
|
System |
Designation |
Remark |
|---|---|---|
|
UNS (USA) |
R30605 |
— |
|
Trade Name |
Haynes® 25 / L-605 (Stellite L-605) |
Haynes International / Kennametal Stellite |
|
DIN / EN |
2.4964 / X40CoCrNiWNi22-20-15 (ref. EN 10095 superalloys) |
Werkstoff-Nr. |
|
China (Aviation / GB) |
GH5605 (also written GH605 in older aerospace docs) |
Closest Chinese spec: GJB 3165, HB 5497 |
|
AMS (Sheet/Strip) |
AMS 5537 |
Solution-annealed sheet & strip |
|
AMS (Bar/Forging) |
AMS 5759 |
— |
|
AMS (Welding Wire) |
AMS 5797 |
ERNiCoCrMo-1 or matching Co-base wire per spec |
|
ISO |
ISO 9723 (superalloys — ref. table) |
— |
⚠️ GH5605 is the Chinese analog of Haynes 25 / L-605. Do not confuse with GH5188 (Haynes 188), which has higher Ni and contains La.
2. Nominal Chemical Composition (AMS 5537 / AMS 5759 Requirement)
|
Element |
Min % |
Max % |
Typical / Goal |
Function |
|---|---|---|---|---|
|
Co |
Bal. |
Bal. |
~47–51 |
Matrix; high-temp microstructural stability |
|
Cr |
19.0 |
21.0 |
20.0 |
Forms Cr₂O₃ protective scale (oxidation resistance) |
|
Ni |
9.0 |
11.0 |
10.0 |
Stabilizes FCC γ-phase (lower than in Haynes 188 → work-hardens faster) |
|
W |
14.0 |
16.0 |
15.0 |
Principal solid-solution strengthener; raises creep resistance |
|
C |
0.05 |
0.15 |
0.10 |
Forms M₂₃C₆ / M₆C at grain boundaries (minor strengthening) |
|
Mn |
— |
1.5 |
0.5–1.0 |
Deoxidant; improves hot workability |
|
Si |
— |
0.40 |
≤0.20 |
Kept low to avoid embrittlement |
|
Fe |
— |
3.0 |
≤1.0 |
Impurity limit |
|
P / S |
— |
0.020 / 0.015 |
— |
Strict impurity control |
|
La / Ce |
— |
— (trace only if any) |
— |
Not intentionally added (key diff. vs. Haynes 188) |
3. Key Physical Properties (Annealed, 20°C Unless Noted)
|
Property |
Value |
Note |
|---|---|---|
|
Density |
9.13 g/cm³ (0.330 lb/in³) |
Slightly heavier than Ni-base |
|
Melting Range |
1330–1410°C (2425–2570°F) |
Solidus ~1330°C |
|
Elastic Modulus (E) |
217–221 GPa @20°C; ~160 GPa @870°C |
— |
|
Mean CTE (20–1000°C) |
~16.5 × 10⁻⁶ /K |
— |
|
Thermal Conductivity |
18 W/m·K @100°C; ~27 W/m·K @800°C |
— |
|
Specific Heat (cp) |
~460 J/kg·K @RT |
— |
|
Electrical Resistivity |
~1.25 µΩ·m @20°C |
— |
|
Magnetic State |
Non-magnetic (FCC γ) at all service temps |
— |
4. Typical Mechanical Properties (Solution-Annealed Condition)
Minimum Requirements — AMS 5537 (Sheet/Strip, annealed):
|
Property |
Minimum (AMS) |
Typical Mill Range |
|---|---|---|
|
Tensile Strength (Rm) |
≥ 895 MPa (130 ksi) |
930–1070 MPa |
|
Yield Strength (Rp0.2) |
≥ 380 MPa (55 ksi) — some AMS refs 310 |
400–480 MPa |
|
Elongation (A50mm) |
≥ 30 % (thick) / ≥ 35 % (thin sheet per some ed.) |
35–50 % |
|
Hardness |
— |
88–98 HRB (190–230 HB) |
Representative Elevated-Temperature Tensile — Typical Annealed Stock:
|
Temp (°C) |
Rm(MPa) |
Rp0.2(MPa) |
Elong. A50(%) |
|---|---|---|---|
|
20 |
960–1040 |
420–480 |
38–50 |
|
540 |
760–830 |
340–390 |
35–45 |
|
760 |
550–610 |
260–310 |
32–40 |
|
870 |
400–450 |
195–235 |
28–36 |
|
980 |
280–330 |
145–180 |
25–32 |
No ductile-to-brittle transition (DBTT): Retains ≥ 30 % elongation at –196°C → suitable for cryogenic valve trim / LOX service.
Creep: Usable to ~760–815°C for moderate stress; 870°C / 70 MPa ~ 100–300 h typical. Not a high-creep disk alloy.
Work Hardening: Higher rate than Haynes 188 (due to lower Ni ≈ 10%); heavy cold work (wire drawing) can reach UTS > 1300 MPa ("spring temper").
5. Oxidation & Corrosion Behavior
Static Air Oxidation: Protective Cr₂O₃ scale to ~1040°C (1900°F) in continuous service. Above this Cr₂O₃ volatilizes as CrO₃.
Cyclic Oxidation / Thermal Shock: No rare-earth doping → oxide scale more prone to cracking/spallation on repeated heating-cooling vs. Haynes 188. For severe cyclic service (> 870°C), Haynes 188 is preferred.
Sulfidation: Superior to Ni-base alloys in fuel-rich, low-O₂/high-S combustion gases (no low-melting Ni–S eutectic).
Seawater / Cl⁻: Not a primary choice (PREN ≈ 22 by Cr only); 316L/625 cheaper for ambient seawater.
Biocompatibility: Passes ASTM F90 (implants); historically used for orthopedic screws, bone plates, and cardiovascular stents (often in cold-drawn spring temper).
6. Fabrication, Welding & Heat Treatment
Hot Working: 1175–1200°C opening; finish > 980°C; air cool or faster. Narrower working window than 188 due to lower Ni.
Cold Working: Work-hardens rapidly — intermediate anneals (1175–1230°C → water quench) required for > 20–30 % total reduction.
Solution Anneal: 1175–1230°C × (time per section) → water quench → dissolve carbides, single γ. Critical for max. ductility.
Welding: GTAW / GMAW / EBW acceptable.
Recommended filler: ERNiCoCrMo-1 (AWS A5.14) or matching Co-base wire (AMS 5797).
No PWHT required for corrosion/oxidation; ≤ 400°C stress relief for dimensional stability.
Machining: Similar to other Co/Ni superalloys — rigid setup, low SFM, high feed, carbide inserts, flood coolant.
7. Typical Applications by Industry
|
Industry |
Component |
Why Haynes 25 (L-605) |
|---|---|---|
|
Legacy Aero / Gas Turbine (MRO) |
Combustor liners (early designs), nozzle guide vanes, afterburner parts on vintage engines |
Historical drawing spec; adequate static oxidation + sulfidation resistance |
|
High-Temp Springs / Seals |
Valve springs, seal rings for turbine / furnace operating 400–650°C |
High work-hardening → spring temper; stress relaxation acceptable in range |
|
Industrial Furnace |
Fixtures, chains, mesh belts (clean oxidizing atm ≤1040°C, static) |
Cheaper than 188 for non-cyclic service; good strength |
|
Biomedical Implants (ASTM F90) |
Bone screws, plates, orthodontic archwires (cold drawn) |
Biocompatible, high modulus, radiopaque, FDA-cleared history |
|
Cryogenic Valves / LOX |
Trim, seats |
No DBTT, galling-resistant when hardened |
8. Brief Historical Note
Developed by Haynes Stellite (later Haynes International) in the late 1940s as a wrought version of Stellite 6 hardfacing alloy — removing the large primary carbides of the cast Stellite 6 while retaining Co–Cr–W solid-solution strength. Originally designated L-605 ("L" for "Low carbon wrought Stellite"), it became an AMS standard (AMS 5537/5759) and was widely adopted in military jet engines of the 1950s–70s. It remains the baseline cobalt alloy for legacy engine overhaul (MRO) and high-temperature spring / implant markets.
9. Summary
Haynes 25 / L-605 (UNS R30605 / GH5605 / 2.4964) is a Co–20Cr–10Ni–15W solid-solution superalloy:
Continuous oxidation resistance to ~1040°C in static air; inferior to Haynes 188 in cyclicoxidation (no La/Ce).
Good strength to 815°C, excellent ductility to –196°C, high work-hardenability → spring wire.
Historically specified on early jet-engine combustor/liner drawings; still the go-to for MRO, high-temp springs, and ASTM F90 implants.
Not age-hardenable; select Haynes 188 for 870–1095°C cyclicoxidation or Inconel 617 for higher creep needs.
Shanghai COCESS Special Alloys Co., Ltd. supplies Haynes 25 (UNS R30605 / GH5605) in sheet, plate, round bar, wire (spring temper available), forged billet, and welding consumables. Material is solution-annealed with EN 10204 3.1 MTR (heat analysis, tensile test, HT record). AMS 5537 / AMS 5759 compliance certification available. Contact our technical department for legacy engine MRO material cross-reference or spring-wire specification support.
Website: https://en.cocessalloys.com
Email: sales@cocessalloys.com
