What is the difference between Elgiloy® and MP35N®?

Elgiloy® offers slightly higher fatigue life and better stress relaxation resistance, making it ideal for dynamic sealing applications with millions of cycles. MP35N® provides higher ultimate tensile strength (up to approximately 2000 MPa depending on condition) and is preferred for high-load, compact spring designs. Both are very low magnetic and corrosion-resistant.

Are Elgiloy® and MP35N® non-magnetic?

Yes. Both alloys have very low magnetic permeability, making them essentially non-magnetic. This property is critical for semiconductor manufacturing equipment, MRI-compatible medical devices, and aerospace instrumentation where magnetic interference cannot be tolerated.

Are Elgiloy® and MP35N® suitable for H₂S / sour gas environments?

Yes. Both Elgiloy® and MP35N® are available for applications requiring NACE MR0175 compliance and offer excellent resistance to sulfide stress cracking (SSC) and corrosion in H₂S environments. They are widely used in downhole tools, wellhead equipment, and subsea sealing applications.

What is the temperature range for cobalt-nickel alloys?

Both alloys perform well from -196°C to approximately 400°C. Elgiloy® exhibits excellent cryogenic ductility down to -253°C. Above 400°C, stress relaxation accelerates; for higher temperatures, consider Inconel® alloys (X-750, 718).

Which material offers the best fatigue life?

Elgiloy® offers the highest fatigue life of any spring material, making it the preferred choice for dynamic sealing applications with high cycle requirements. MP35N® also provides excellent fatigue resistance but is slightly surpassed by Elgiloy® in this specific property.

Can 316L stainless steel replace cobalt-nickel alloys?

No — for applications requiring very low magnetic properties, superior fatigue life, or H₂S resistance, 316L stainless cannot replace cobalt-nickel alloys. 316L is magnetic (after cold work), has lower fatigue strength, and is not NACE MR0175 compliant. Cobalt-nickel alloys are premium materials for mission-critical applications where 316L would fail.

Why are cobalt alloys preferred over stainless steel?

Cobalt-nickel alloys offer significantly higher fatigue life, better stress relaxation resistance, very low magnetic permeability, and superior corrosion resistance compared to standard stainless steels. While they come at a premium cost, they are the only choice for applications demanding extreme reliability, magnetic neutrality, or H₂S resistance.

Can cobalt-nickel alloys be used in dynamic seals?

Yes — Elgiloy® and MP35N® are among the best materials for dynamic sealing applications due to their exceptional fatigue life, stress relaxation resistance, and corrosion resistance. They are widely used in reciprocating and rotary sealing systems where long service life and consistent performance are critical.

Are these materials suitable for vacuum service?

Yes — both Elgiloy® and MP35N® are suitable for vacuum and semiconductor applications due to their low outgassing properties and very low magnetic permeability. They are commonly used in vacuum chambers, semiconductor processing equipment, and high-purity gas handling systems.

What spring types can be manufactured from these alloys?

Handa Spring manufactures a wide range of spring types from cobalt-nickel alloys, including canted coil springs, helical spring energizers, cantilever V/U springs, full-contact springs, and detached-leg springs. Custom geometries are available upon request.

What is the most cost-effective material for general-purpose spring energizers?

302 Stainless Steel offers the best balance of cost and performance for general-purpose spring energizer applications. 17-7PH provides higher strength at a moderate cost premium. Cobalt-nickel alloys are recommended only when application demands justify their premium cost.

Do you provide material certifications for spring products?

Yes. We provide material certificates (3.1, 3.2) and compliance certifications (RoHS, REACH, NACE MR0175) upon request. Full material traceability is maintained for all spring products.

Cobalt Nickel Alloys For Spring Energizers | Elgiloy & MP35N

Overview Why Cobalt-Nickel? Key Properties Comparison Spring Applications Selection Matrix Applications Design Considerations FAQ Recommended Designs Get Quote

Why Choose Cobalt-Nickel Alloys

Key Performance Advantages

Elgiloy® and MP35N® deliver unmatched performance in extreme environments.

Very Low Magnetic Permeability

Essentially non-magnetic — essential for semiconductor, medical (MRI), and aerospace applications.

Superior Fatigue Life

Highest fatigue resistance among all spring materials. Ideal for dynamic seals with millions of cycles.

Exceptional Corrosion Resistance

Withstands H₂S (sour gas), seawater, chlorides, and aggressive media. Available for NACE MR0175 compliance.

Stress Relaxation Resistance

Maintains spring force over extended service life, even at elevated temperatures and under constant load.

Cryogenic Stability

Retains elasticity and toughness at temperatures as low as -196°C, suitable for LNG and cryogenic sealing.

High Strength

MP35N® achieves tensile strength up to approximately 2000 MPa depending on condition, enabling compact spring designs with high load capacity.

Selection Tool

Material Comparison

Compare cobalt-nickel alloys with other common spring materials to see why they are the premium choice.

Property	Elgiloy®	MP35N®	Inconel® X750	17-7PH	316L
Corrosion Resistance	Excellent	Excellent	Good	Moderate	Good
Fatigue Life	Excellent	Excellent	Good	Good	Moderate
Stress Relaxation	Outstanding	Excellent	Good	Moderate	Moderate
Magnetic Permeability	Very Low	Very Low	Magnetic	Magnetic	Magnetic
Sour Gas (H₂S)	Available	Available	Limited	Limited	Not Recommended
Cryogenic Performance	Excellent	Good	Excellent	Moderate	Good
High Temperature	Good (~400°C)	Good (~400°C)	Excellent (>600°C)	Moderate (~350°C)	Moderate (~400°C)
Relative Cost	High	Very High	High	Low	Low

Performance ratings are general engineering references. Actual performance depends on heat treatment, cold work, and specific application conditions. Contact us for detailed material data sheets.

Spring Applications

Typical Spring Energizer Applications

Each spring type has specific material requirements based on load, motion, temperature, and media compatibility.
Below is a general guide to material selection for each spring design.

Spring Type	Typical Materials	Key Characteristics
Helical Spring Energizers	302, 17-7PH, Elgiloy, Inconel X750, Inconel 718	High load capacity, wide temperature range, dynamic sealing
Canted Coil Spring Energizers	Elgiloy, MP35N, Inconel 718, Hastelloy C-276	Constant force, low friction, non-magnetic options, extreme corrosion
Cantilever V Spring Energizers	302, 316L, 17-7PH, Elgiloy	Low deflection, high force, general industrial sealing
Cantilever U Spring Energizers	302, 17-7PH, Elgiloy	Moderate deflection, good force retention, compact designs
Full Contact Spring Energizers	Inconel X750, Inconel 718, Elgiloy, MP35N	High temperature, corrosion resistance, EMI shielding
Detached Leg Spring Energizers	302, 316L, Elgiloy	Custom geometries, low cost, moderate corrosion

Material recommendations are general guidelines. Actual selection depends on operating temperature, media, load cycle, and cost targets. Contact our engineering team for application-specific recommendations.

Quick Selection

Typical Material Selection Matrix

Match your application requirement with the recommended cobalt-nickel alloy.

Highest fatigue life Elgiloy®

Highest strength MP35N®

Very low magnetic permeability Elgiloy® / MP35N®

Sour gas / H₂S service Elgiloy® / MP35N®

Medical / implantable devices MP35N®

Semiconductor / vacuum sealing Elgiloy®

Compact spring designs MP35N®

Cryogenic / LNG service Elgiloy®

Not sure which alloy fits your application? Contact our engineering team for personalized selection support.

Applications

Where Cobalt-Nickel Alloys Excel

Elgiloy® and MP35N® are the materials of choice for mission-critical sealing applications across multiple industries.

Semiconductor

Elgiloy®, MP35N®
Low outgassing, very low magnetic, high purity

Medical Devices

MP35N®, Elgiloy®
Biocompatible, MRI-safe, very low magnetic

Aerospace

MP35N®, Elgiloy®
High strength, fatigue, very low magnetic

Oil & Gas

Elgiloy®, MP35N®
H₂S resistant, NACE MR0175 available

LNG & Cryogenic

Elgiloy®, MP35N®
-196°C stability, thermal cycling

Chemical Processing

Elgiloy®, MP35N®
Acid resistance, corrosion resistance

Marine & Offshore

Elgiloy®, MP35N®
Seawater, chloride pitting resistance

Hydrogen Energy

Elgiloy®, MP35N®
Hydrogen embrittlement resistance

Analytical Instruments

Elgiloy®, MP35N®
High precision, low magnetic interference

Vacuum Equipment

Elgiloy®, MP35N®
Low outgassing, thermal stability

Downhole Tools

Elgiloy®, MP35N®
H₂S resistant, high strength, NACE available

Subsea Systems

Elgiloy®, MP35N®
Seawater corrosion, high reliability

Industry-specific applications: For semiconductor wafer processing, Elgiloy® and MP35N® provide low outgassing and very low magnetic properties essential for cleanroom environments. For medical devices, both alloys offer MRI compatibility and biocompatibility. For oil & gas H₂S service, they are available for applications requiring NACE MR0175 compliance.

Engineering Guidance

Design & Selection Considerations

Key factors to consider when specifying cobalt-nickel alloys for your spring energizer.

Spring Design

Cobalt-nickel alloys have high modulus of elasticity (~200–210 GPa). Spring force calculations should account for this. View design guide →

Machinability

Both Elgiloy® and MP35N® are work-hardening alloys. They require specialized tooling and machining parameters. Contact engineering →

Heat Treatment

MP35N® can be aged to achieve ultimate tensile strength up to approximately 2000 MPa depending on condition. Elgiloy® is typically used in the cold-worked condition.

Cost vs. Value

Cobalt-nickel alloys are premium materials. They are cost-effective when application demands non-magnetic properties, extended fatigue life, or H₂S resistance.

Need help selecting between Elgiloy® and MP35N®? Our engineering team can analyze your application requirements — temperature, pressure, media, cycle life, and cost targets — and recommend the optimal alloy. Request engineering support →

Design Recommendations

Recommended Spring Designs

Based on the properties of cobalt-nickel alloys, these materials are commonly used in the following
spring energizer designs.

Elgiloy®

Highest fatigue, non-magnetic

Canted Coil Helical Full Contact

MP35N®

Ultra-high strength, non-magnetic

Canted Coil Helical Full Contact

Select a spring design to learn more about its unique requirements and capabilities. View all spring designs →

Cobalt-Nickel Alloys for Spring Energizers

What Are Cobalt-Nickel Alloys?

Why Cobalt-Nickel Alloys?

Elgiloy®

MP35N®

Key Performance Advantages

Very Low Magnetic Permeability

Superior Fatigue Life

Exceptional Corrosion Resistance

Stress Relaxation Resistance

Cryogenic Stability

High Strength

Material Comparison

Typical Spring Energizer Applications

Typical Material Selection Matrix

Where Cobalt-Nickel Alloys Excel

Semiconductor

Medical Devices

Aerospace

Oil & Gas

LNG & Cryogenic

Chemical Processing

Marine & Offshore

Hydrogen Energy

Analytical Instruments

Vacuum Equipment

Downhole Tools

Subsea Systems

Design & Selection Considerations

Spring Design

Machinability

Heat Treatment

Cost vs. Value

Frequently Asked Questions

Recommended Spring Designs

Elgiloy®

MP35N®

Ready to Specify Cobalt-Nickel Alloys?