When should I choose a high-temperature alloy over stainless steel?

Choose a high-temperature alloy when your operating temperature exceeds 550°F (288°C) continuously, when thermal cycling is present, or when stress relaxation at elevated temperatures would cause stainless steel springs to lose sealing force. Inconel alloys maintain significantly higher force retention at elevated temperatures compared to standard stainless steels.

What is the difference between Inconel X-750 and Inconel 718 for springs?

X-750 offers superior creep-rupture strength and stress relaxation resistance at the highest service temperatures, making it ideal for sustained high-temperature applications. 718 provides excellent strength and ductility in the intermediate temperature range with better cryogenic ductility. Choose X-750 for the highest service temperatures, 718 for intermediate temperatures or high-strength cryogenic applications.

Which Inconel alloy offers the best stress relaxation resistance?

Inconel X-750 offers the best stress relaxation resistance among high-temperature nickel alloys. At elevated service temperatures, X-750 maintains significantly higher initial stress after extended periods compared to Inconel 718, making it the preferred choice for springs requiring long-term load retention in severe thermal environments.

Is Inconel 625 suitable for seawater applications?

Yes. Inconel 625 is resistant to chloride-ion stress-corrosion cracking, pitting, and crevice corrosion, making it highly suitable for seawater and marine environments. This distinguishes it from X-750 and 718, which have only moderate chloride resistance.

Why isn't Inconel 625 recommended above 550°C for springs?

Inconel 625 is a solid-solution strengthened alloy without precipitation-hardening phases. Above 550°C, its stress relaxation resistance decreases significantly compared to precipitation-hardened alloys like X-750 and 718. While 625 can physically withstand higher temperatures, spring force retention at 600°C is substantially lower than X-750, making it less suitable for long-term high-temperature spring applications.

Can different spring designs use the same alloy?

Yes. Inconel X-750, 718, and 625 are available in both precision wire and strip forms, making them suitable for all major spring energizer designs — including helical, canted coil, cantilever, full contact, detached leg, and garter springs. The same alloy can be used across multiple spring types, depending on the specific application requirements.

What spring types can be manufactured from Inconel alloys?

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

Can Inconel springs operate continuously at elevated temperatures?

Yes, but with considerations. Inconel X-750 and 718 are designed for extended service at elevated temperatures. However, the maximum continuous service temperature depends on the specific alloy, heat treatment, and allowable stress relaxation. For long-term service above 600°C, X-750 is the preferred choice.

High Temperature Materials For Spring Energizers | Selection Guide

Why High Temperature

Why Do Spring Energizers Need High Temperature Materials?

At elevated temperatures, conventional stainless steel springs lose force through a process called
stress relaxation— the gradual reduction of spring force over time when held at a constant deflection. As temperature increases, atomic diffusion accelerates, allowing dislocations to move and relieve internal stresses. This causes the spring to lose sealing force, potentially leading to leakage or seal failure.

Standard stainless steels such as 302 and 316L are typically limited to continuous service temperatures up to 500–550°F (260–288°C) for spring applications. Above these temperatures, stress relaxation becomes significant, and spring force retention decreases rapidly.

If your spring must maintain sealing force after thousands of hours at elevated temperature, selecting a high-temperature nickel alloy is often more important than simply choosing a stronger material.

When should you upgrade to a high-temperature alloy?

Continuous service above — 288°C (550°F)
Long-term spring force retention is required
Frequent thermal cycling between elevated and ambient temperatures
High-temperature oxidation exposure
Creep resistance under constant compression

Selection Flow

Engineering Material Selection Matrix

Select a recommended spring alloy by matching your operating temperature with your application’s primary engineering requirement. This matrix provides a quick starting point for material selection. Detailed property comparisons are available in the Alloy Comparison section below.

Engineering Requirement

Below 300°C (moderate)

300–450°C (elevated)

450–600°C (high)

Above 600°C (extreme)

Standard Industrial Applications General industrial equipment with moderate loads and non-corrosive environments.

302 316L 17-7PH

X-750

Corrosive Process Media Acids, chlorides, seawater, sour gas, chemical processing.

316L Elgiloy

625

625 *

Engineering Review Required

High Spring Load Compact spring cavities requiring maximum spring force.

17-7PH

718

X-750

Dynamic / High Fatigue Frequent cycling, low friction, long fatigue life.

Elgiloy

Elgiloy (up to 450°C)

X-750 718

X-750

Below 300°C 300–450°C 450–600°C Above 600°C Primary recommendation Elgiloy (specialty) * 625 may be considered with reduced service life

Note: This matrix provides an initial material recommendation. Final alloy selection should also consider spring geometry, required sealing force, manufacturing process, service life, and specific media compatibility.

Continue below for detailed alloy comparison and selection guidance ↓

Alloy Matrix

High Temperature Alloy Comparison

Every alloy is optimized for a different engineering priority rather than being universally “better.” Use this table to understand material differences.

Property	Inconel X-750	Inconel 718	Inconel 625
Alloy Type	Ni-Cr, γ’ precipitation	Ni-Cr-Columbium, γ” precipitation	Ni-Cr-Mo, solid-solution
Max Spring Service Temp	~650°C	~600°C	~550°C
Stress Relaxation (650°C)	★★★★★	★★★☆☆	★★☆☆☆
Spring Force Stability	★★★★★	★★★★☆	★★★☆☆
Yield Strength	Good	Highest	Moderate
Corrosion Resistance	Good	Good	Outstanding
Oxidation Resistance	★★★★★	★★★★☆	★★★★☆
Thermal Cycling Stability	★★★★★	★★★★☆	★★★☆☆
Cryogenic Ductility	★★★★☆	★★★★★	★★★☆☆
Cold Formability	★★★☆☆	★★★★☆	★★★★☆
Relative Cost	High	High	Very High

Ratings are for spring applications. Actual performance depends on heat treatment, spring design, and operating conditions.

When Engineers Typically Choose Each Alloy

Inconel X-750

Choose when:

Continuous service above 550°C
Long spring force retention
Oxidizing atmosphere
Thermal cycling

Learn more →

Inconel 718

Choose when:

High spring stress
Limited installation space
Cryogenic + elevated temperature
High strength

Learn more →

Inconel 625

Choose when:

Aggressive chemicals
Marine equipment
Chloride media
Corrosion is more critical than maximum temperature

Learn more →

Still unsure?Material selection is rarely based on temperature alone. Long-term spring performance depends on the combined effects of load, corrosion, geometry, thermal cycling, and manufacturing method.
Contact our engineering teamfor application-specific recommendations.

Spring Applications

Compatible Spring Energizer Designs

All spring types can be manufactured in high-temperature nickel alloys. Each design is suited for specific sealing applications.

Helical Spring

For static sealing requiring long-term load retention at elevated temperatures. Suitable for high-pressure and moderate-deflection applications.

X-750 · 718 · 625 Learn More →

Canted Coil Spring

Ideal where low friction and consistent force are required under repeated thermal cycling. Wide deflection range with nearly constant force.

X-750 · 718 · 625

Learn More →

(U Spring / V Spring) Cantilever Spring (U/V)

Overview: Recommended for dynamic sealing applications requiring both flexibility and heat resistance. Suitable for limited installation space.

X-750 · 718

Learn More →

Full Contact Spring

Overview: Designed for vacuum and gas sealing where continuous circumferential contact is required. Provides enhanced sealing performance at elevated temperatures.

X-750 · 718

Learn More →

Detached Leg Spring

Overview: Custom sealing geometries where independent leg placement is required for specific installation constraints. Flexible design options.

X-750 · 718 · 625

Learn More →

Garter Spring

Overview: Rotary shaft sealing requiring stable radial loading. Suitable for dynamic sealing applications with thermal exposure.

X-750 · 718 · 625

Learn More →

Material availability:Inconel X-750, Inconel 718, and Inconel 625 are available in both precision wire and strip forms, supporting all spring types listed above.
View all spring designs →

Why Handa

How We Help Your Project

Decades of experience manufacturing custom spring energizers in high-temperature nickel alloys.

Material Selection Support

We recommend suitable alloys based on operating temperature, media, spring geometry, and expected service life — not just material availability.

Manufacturing Flexibility

Both precision wire and strip forms are processed in-house, enabling all major spring energizer configurations from a single material platform.

Faster Prototype Development

Large existing tooling library reduces lead time for standard geometries. Custom tooling is available for new profiles and unique spring designs.

Verified Spring Performance

Each production batch is verified using calibrated force testing equipment to ensure spring force meets customer specifications.

Controlled Heat Treatment Process

Precipitation hardening and stress relieving services are performed in-house for X-750, 718, and other heat-treatable alloys.

Prototype to Mass Production

We support prototype development, small-batch qualification, and volume production — all from the same manufacturing platform.

Over the years, Handa Spring has supplied custom high-temperature spring energizers to seal manufacturers, engineering firms, and equipment OEMs across North America, Europe, and Asia. Our objective is to become part of our customers’ engineering process—from prototype development through long-term production.

Selection Guide

Engineering Selection Guide

Real-world application scenarios showing how engineers select the right alloy for their specific challenges.

Gas Turbine Seal

Challenge: Continuous operation above 600°C with repeated thermal cycling.

Inconel X-750

Reason: Excellent stress relaxation resistance ensures long-term sealing force under the most demanding thermal conditions.

High-Load Actuator Spring

Challenge: Limited installation space requiring maximum spring force in a compact design at 500°C.

Inconel 718
Reason: Highest yield strength among high-temperature alloys enables smaller cross-sections without sacrificing load capacity.

Chemical Reactor Seal

Challenge: 450°C operation with aggressive chemical media requiring both heat and corrosion resistance.

Inconel X-750

Reason: Superior corrosion resistance combined with thermal stability makes 625 the only choice for chemically aggressive high-temperature environments.

Subsea Connector Spring

Challenge: Elevated temperature with seawater exposure and chloride stress-corrosion cracking risk.

Inconel 625

Reason: Outstanding resistance to chloride-induced SCC and pitting makes 625 the preferred material for offshore and marine environments.

Aerospace Control Spring

Challenge: 600°C service with high reliability requirements and thermal cycling.

Inconel X-750

Reason: Proven track record in aerospace applications requiring long-term load retention and oxidation resistance at elevated temperatures.

LNG Cryogenic Seal

Challenge: -196°C to 400°C thermal cycling with toughness requirements at cryogenic temperatures.

Inconel 718

Reason: Excellent ductility across the full temperature range from cryogenic to elevated temperatures makes 718 ideal for LNG applications.

High-Frequency Dynamic Seal

Challenge: Millions of cycles at 400°C with demanding fatigue requirements.

Elgiloy

Reason: Elgiloy offers the highest fatigue life among spring materials, combined with excellent corrosion resistance and non-magnetic properties — ideal for dynamic sealing applications.

Non-Magnetic High-Temp Seal

Challenge: 400°C operation with strict non-magnetic requirements for sensitive instrumentation.

Elgiloy

Reason: Elgiloy is non-magnetic and retains excellent spring properties up to 450°C, making it the preferred choice for medical and sensitive electronic equipment.

Need a custom recommendation?Our engineering team can analyze your operating temperature, sealing media, spring geometry, and performance requirements to recommend the optimal material.
Contact us →

High Temperature Materials for Spring Energizers — Selection Guide

Why Do Spring Energizers Need High Temperature Materials?

Engineering Material Selection Matrix

High Temperature Alloy Comparison

When Engineers Typically Choose Each Alloy

Inconel X-750

Inconel 718

Inconel 625

Compatible Spring Energizer Designs

Helical Spring

Canted Coil Spring

(U Spring / V Spring) Cantilever Spring (U/V)

Full Contact Spring

Detached Leg Spring

Garter Spring

How We Help Your Project

Material Selection Support

Manufacturing Flexibility

Faster Prototype Development

Verified Spring Performance

Controlled Heat Treatment Process

Prototype to Mass Production

Engineering Selection Guide

Gas Turbine Seal

High-Load Actuator Spring

Chemical Reactor Seal

Subsea Connector Spring

Aerospace Control Spring

LNG Cryogenic Seal

High-Frequency Dynamic Seal

Non-Magnetic High-Temp Seal

Frequently Asked Questions

Ready to Select Your High Temperature Spring Material?

What to Test in a Canted Coil Spring Sample Request

Why Canted Coil Spring Sample Testing Is Critical Before Production

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