Complete High-Temperature Property Table of Haynes 25: Tensile, Creep & Oxidation Rates (20–1040°C)

Haynes 25 (UNS R30605 / W.Nr. 2.4964 / China GH5605), also known as L-605, is a solid-solution strengthened cobalt-chromium-nickel-tungsten superalloy containing 19–21% Cr, 9–11% Ni, 14–16% W, and ~0.10% C. It is notprecipitation-hardenable and derives its elevated-temperature strength from W and Cr solute atoms plus minor grain-boundary M₂₃C₆ / M₆C carbides.

This article consolidates the quantitative high-temperature dataset for Haynes 25 — tensile properties, representative creep-rupture values, oxidation kinetics in static air, and relevant physical constants — based on Haynes International technical data, AMS 5537/5759 references, and ASM Handbook Vol. 2 (Properties of Precious and Superalloys). The intent is to provide designers and materials engineers with a single reference for preliminary sizing, thermal stress input, and corrosion-allowance estimation in the 20–1040°C (68–1920°F) range.

1. Physical Constants (Temperature Dependent)

CTE values are mean coefficients referenced to 20°C. Dynamic E by sonic method.

2. Tensile Properties vs. Temperature (Solution-Annealed Condition, Typical)

Data below are typical averages for solution-annealed sheet/plate (1175–1230°C → water quench).

AMS 5537 minimum requirements (sheet): Rm ≥ 895 MPa, Rp0.2 ≥ 380 MPa (some refs ≥310), A ≥ 30–35%.

Key observations:

• No ductile-to-brittle transition — elongation > 30% even at –196°C (test data: ~45% RA, 38% A at LN₂ temp).

• Strength retention to 760°C is good for a solid-solution alloy; above 870°C strength declines rapidly — design as lightly stressed sheet/spring, not primary turbine disk.

3. Creep-Rupture / Stress-Rupture Typical Values (Reference Only)

Haynes 25 is notcovered by ASME Section II-D creep tables for design; values below are typical isothermal rupture trends​ from producer data for estimation only.

→ For primary load-bearing > 760°C long-term, consider Inconel 617 or Haynes 188 (marginally better creep); Haynes 25 is optimized for self-supported or lightly stressed hot-section sheet, springs, and seals.

4. Oxidation / Corrosion Rate Data (Static Air / Flue Gas)

4.1 Static Air Oxidation (Continuous Exposure)

4.2 Cyclic Oxidation (Heat ↔ Cool)

Test: 980°C × 1 h hold ↔ air cool to RT × 15 min cycles.

→ Haynes 25 is acceptable for static high-T oxidation (furnace fixtures, legacy combustor liners in steady-state run)​ but not preferred for severe thermal cycling (> 870°C ↔ RT repeatedly)​ — then upgrade to Haynes 188.

4.3 Sulfidizing / Mixed Combustion Gas (Fuel-Rich, low O₂ + S-species)

• Superior to Ni-base (Inconel 617/625) due to absence of low-melting Ni–S eutectic (mp ~ 625°C).

• Qualitative ranking: Good (better than Ni-base) in fuel-rich partially oxidized combusted gases​ at ≤ 980°C.

4.4 Other Media

• Seawater / Cl⁻: not recommended (PREN ≈ 22–24 by Cr only — 316L/625 cheaper for ambient seawater)

• Strong oxidizing acids (HNO₃, hot conc. H₂SO₄ + oxidant): poor

5. Thermal Expansion & Stress Calculation (Worked Example)

Thermal strain for a free unconstrained bar from 20°C → T:

ε_th(T) ≈ α_mean(20–T)× (T – 20)

Example: 20 → 800°C, α ≈ 16.2×10⁻⁶/K

ε_th= 16.2×10⁻⁶ × 780 ≈ 0.01264 ≈ 1.26 % linear expansion

Thermal stress if fully constrained: σ = E(T) × ε_th. At 800°C, E ≈ 166 GPa → σ ≈ 210 MPa (indicative; relaxed by creep in service).

6. Recommended Design Temperature Limits

7. Summary Data Takeaways

• Tensile:​ Rm 960–1040 MPa @ RT → 280–330 MPa @ 980°C; Rp0.2 420–480 → 145–180 MPa over same range; A > 35% @ RT, > 25% @ 980°C.

• Creep:​ Usable ~870°C / 70 MPa for ~1000 h class; not a high-creep disk alloy — for lightly stressed sheet/spring/seal.

• Oxidation:​ Continuous to 1040°C in static air; no rare-earth → scale spalls under thermal cycling​ (vs. Haynes 188 with La). Sulfidation resistance better than Ni-base.

• Physical:​ ρ=9.13 g/cc, E_20°C=219 GPa, CTE_{20–1000°C(mean)}=16.5×10⁻⁶/K, non-magnetic FCC.