Is Inconel 625 suitable for seawater and marine sealing energizers?

Yes — INCONEL® 625 is widely used in seawater/brackish environments for its strong pitting and crevice resistance; confirm finished surface and fatigue requirements with your supplier and perform representative testing for cyclic corrosion fatigue.

Can cold-drawn Inconel 625 spring wire reach very high UTS?

Yes — while annealed tensile is typically ~100-140 ksi, heavy cold work used for spring wire production commonly raises UTS significantly (wire UTS >200 ksi often achievable; exact values depend on cold reduction and diameter — check supplier tables).

What temperature guidance should I use when designing energizers?

Use supplier stress-relaxation and creep tables for your chosen temper & diameter. Short-term property retention can extend to high temperatures, but recommended long-term continuous temperatures are much lower; always calibrate design against supplier data and test components for representative conditions.

For sour H2S service which materials should I prioritise?

For critical sour H2S service Elgiloy and MP35N are often prioritised due to strong SSC resistance at high strength; Inconel 625 may be suitable in some sour conditions but project NACE/ISO qualification and hardness limits are typically required.

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event2025年9月28日
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INCONEL® 625 is a nickel–chromium–molybdenum–niobium solid-solution alloy widely used where **corrosion resistance**, **good ductility**, and the ability to be **cold-worked to high strength** are required. It is a common choice for spring-energized seals and energizers in marine, chemical processing, aerospace and subsea applications.

Contents

Introduction & quick summary
Core characteristics
Typical applications
Forming into springs & spring types
Alternatives & comparison
Selection guidance
FAQ
References

Introduction & quick summary

INCONEL® alloy 625 (UNS N06625) offers a strong balance of corrosion resistance and cold-work hardenability. Designers choose 625 when **pitting/crevice resistance**, weldability, and good high-temperature corrosion behaviour are required for energizers. For high-temperature preload retention compare with INCONEL X-750, and for extreme sour/SSC cases compare with Elgiloy or MP35N.

Need custom INCONEL® 625 springs or technical guidance? Request a quote — provide operating fluid, temperature range and gland geometry.

Core characteristics

Typical chemical composition

Typical composition ranges (confirm exact lot values on supplier mill certificate):

Element	Typical (wt.%)
Nickel (Ni)	≥ 58.0%
Chromium (Cr)	20.0–23.0%
Molybdenum (Mo)	8.0–10.0%
Niobium (Nb) + Tantalum (Ta)	≈ 3.15–4.15%
Iron (Fe)	≤ 5.0%
Carbon (C)	≤ 0.10%
Mn / Si	≤ 0.50% each

Key physical data (typical)

Typical physical & thermal properties — always verify with the supplier datasheet for the chosen product form and temper:

Property	INCONEL® 625 (typical)
Density	≈ 8.44 g/cm³ (≈ 0.305 lb/in³)
Modulus of Elasticity (E)	≈ 28–30 ×10⁶ psi (≈ 190–207 GPa) (room temperature)
Modulus of Rigidity (G)	≈ 11.0–12.0 ×10⁶ psi (≈ 76–83 GPa)
Coefficient of thermal expansion	Temperature-dependent — consult supplier tables
Typical tensile strength (annealed)	≈ 100–140 ksi (≈ 690–965 MPa); cold-worked spring wire often exceeds 200 ksi depending on reduction and diameter — verify with supplier wire charts.
Min service temperature	≈ −200°C (cryogenic suitability; verify with supplier product form).
Short-term / intermittent max	Properties retained for short periods up to ≈ 1800°F (≈ 982°C).
Recommended long-term continuous	Conservative guidance commonly ≤ ≈ 1100°F (≈ 593°C). For springs always use supplier stress-relaxation & creep tables for the specific diameter and temper.

Core capabilities — why designers choose 625

Excellent resistance to pitting & crevice corrosion — ideal for chloride-containing and marine environments.
Good chloride SCC resistance in many service conditions (design with appropriate hardness and qualification testing).
Cold work hardenability — solid solution alloy that can be cold-drawn to higher strengths for spring wire.
Good weldability & formability compared with some precipitation-hardened alloys.
Versatile product forms — suitable for a broad range of energizer geometries.

Typical applications

Sealing energizers and canted coil springs for chemical processing and marine environments.
PTFE and elastomeric seals requiring corrosion-resistant energizers (spring-energized seals).
High-performance fasteners, clips and components where corrosion resistance and cold-work strength are required.
Garter and oil & gas springs used in moderate high-temperature and chloride environments (Garter / Oil & Gas Springs).

Forming into springs & spring types

Reminder: spring energizers are formed from wire (round or profiled) or strip. INCONEL 625 is available in spring wire and strip — confirm diameter, temper and available product form with your wire supplier.

Inconel 625 Cobalt Nickel Alloys Helical Spring | Handa Springs

Inconel 625 Garter Spring(Oil &gas Spring Seals)

Inconel 625 Helical Springs | Handa Spring

Inconel 625 Cantilever V Springs / Cantilever U Springs | Handa Spring

Forming & finishing notes

Cold drawing and cold coiling are commonly used to achieve spring temper — final mechanicals depend strongly on cold reduction and wire diameter; check supplier diameter-by-temper charts.
Surface finishing (electropolish/mechanical) significantly improves corrosion fatigue life.
When springs will see sustained elevated temperatures, qualify a final aging schedule and request stress-relaxation data from the supplier for the targeted operating temperature.

Alternatives & comparison

Comparison of commonly considered alternatives for spring energizers — Min/Max service temperatures, corrosion / behaviour, and typical strength. Values are engineering guidance consolidated from supplier datasheets; always verify with the mill certificate and temper-specific stress-relaxation data.

Material	Corrosion / behaviour	Strength (typical)	Min service temp	Short-term max temp	Recommended long-term continuous temp
INCONEL 625 (UNS N06625)	Excellent pitting/crevice resistance; good chloride SCC resistance	~100–140 ksi (annealed); cold-drawn >200 ksi	≈ −200 °C	≈ 982 °C (≈ 1800 °F)	≈ 593 °C (≈ 1100 °F)
INCONEL X-750 (UNS N07750)	Good oxidation; engineered for low relaxation at high T	High (precipitation-hardened)	≈ −200 °C	≈ 982 °C (≈ 1800 °F)	≈ 704 °C (≈ 1300 °F)
INCONEL 718 (UNS N07718)	Very good corrosion; high strength after aging	Very high (age-hardened)	≈ −250 °C	≈ 760 °C (≈ 1400 °F)	≈ 538–593 °C (≈ 1000–1100 °F)
Hastelloy C-276	Outstanding chemical resistance (strong acids/chlorides)	Moderate	≈ −196 °C	≈ 538 °C (≈ 1000 °F)	≈ 371 °C (≈ 700 °F) — application dependent
Elgiloy® (cobalt-nickel)	Excellent SSC & corrosion fatigue; great elastic recovery	Very high (cold-worked)	≈ −200 °C	≈ 454 °C (≈ 850 °F)	≈ 454 °C (≈ 850 °F)
MP35N®	Excellent SSC, chloride & hydrogen resistance	Very high (work-hardened)	≈ −200 °C	≈ 399 °C (≈ 750 °F)	≈ 399 °C (≈ 750 °F)
17-7 PH / 316L	Good general corrosion; 17-7 PH excellent spring properties	Moderate to high (depends on temper)	Varies (often ≈ −196 to −250 °C ranges)	Varies (material dependent)	Typically much lower than nickel superalloys — consult supplier

Note: “Min service temp” indicates typical cryogenic/low-temperature suitability; “Short-term max temp” indicates property or hot-work limits; “Recommended long-term continuous temp” is a conservative engineering guidance for prolonged use of springs. Always design from supplier stress-relaxation & mill data for the selected temper/diameter.

Selection guidance

Concise selection rules — pick the alloy that best matches your dominant constraint:

Dominant: Corrosion in chloride / marine environments — choose INCONEL 625 (excellent pitting/crevice resistance; good seawater performance).
Dominant: Long-term preload & creep resistance at very high temperature — choose INCONEL X-750 (precipitation-hardened for relaxation resistance).
Dominant: Highest strength & toughness — choose INCONEL 718 (age-hardenable with excellent UTS/YS).
Dominant: Sulfide stress cracking / sour gas (SSC) — prioritise Elgiloy or MP35N and require NACE MR0175 / ISO 15156 qualification.
Dominant: Elastic recovery & fatigue in miniature springs — choose Elgiloy or MP35N.
Cost / moderate conditions — consider 17-7 PH or 316/316L for non-sour, lower-temperature applications.

Quick validation checklist (must-do)

Obtain supplier mill certificate and diameter-by-temper mechanical tables (UTS / YS / hardness).
Request stress-relaxation / creep curves at the intended operating temperature and diameter.
Specify representative fatigue + corrosion test coupons (same finish, join method and geometry) for qualification when required.

FAQ

Q1: What temperature range can INCONEL 625 operate in?

A1: Typical min service temp ≈ −200°C; short-term properties may be retained up to ≈ 982°C (1800°F); recommended conservative long-term continuous service is ≈ 593°C (1100°F). Always confirm with supplier data for your temper and diameter.

Q2: Is INCONEL 625 suitable for sour H₂S service?

A2: 625 is corrosion-resistant in many environments, but for critical sour H₂S / SSC risk designers commonly prefer Elgiloy or MP35N and require NACE MR0175 / ISO 15156 qualification and hardness control.

Q3: What spring types are typically produced from INCONEL 625?

A3: Canted coil, helical, cantilever V/U springs, full contact and garter springs — availability depends on wire diameter and supplier capabilities.

Q4: How should I verify that INCONEL 625 will meet my spring performance needs?

A4: Request mill certificate, diameter-by-temper tables, stress-relaxation curves, and run representative force-deflection, fatigue and corrosion tests on production-intent parts or coupons.

Inconel 625