Elinvar Alloy | Lork
Product Introduction
Elinvar (nominal composition: approx. 33–35% nickel, 4–5% chromium, 1–3% tungsten, balance iron) is a nickel-iron-chromium-based precision elastic alloy; its name is derived from the French phrase *élasticité invariable*-meaning "invariable elasticity."
The material's core value lies in the fact that its temperature coefficient of the modulus of elasticity (β_E) remains virtually zero across a very wide temperature range. Simply put, if a spring made of this material is installed in a precision instrument, the spring force remains constant regardless of whether it is summer or winter. For components like watch hairsprings, gyroscope springs in navigation systems, or pressure gauge capsules, any data drift caused by temperature fluctuations would render the precision instrument useless. Elinvar is designed specifically for such "constant elasticity" applications, making it ideal for rigorous operating conditions where instruments must function reliably across extreme environments-from the skies to the depths of the earth.
Its typical applications span several high-end sectors:
Horology and precision timekeeping: Hairsprings and mainsprings for watches and marine chronometers; its "constant elasticity" physically ensures timekeeping accuracy.
Aerospace: Core elastic components for gyroscopes and accelerometers, as well as various precision sensors operating across wide temperature ranges.
Precision instrumentation: Capsules, diaphragms, bellows, tension strips, and suspension wires used in various precision measuring instruments.
Electronics industry: Frequency-determining components for resonators and filters.
Medical devices: High-precision medical equipment and sensors that rely on this temperature-independent elastic property.
High-end valves and seals: Precision valve springs and sealing elements requiring long-term stability, such as those used in the petrochemical and aerospace industries.
Differences from Invar
These are two materials most easily confused with each other. Elinvar and Invar are "sibling alloys"-both invented by Guillaume-yet they serve vastly different purposes:
- Elinvar: Focuses on the elastic modulus-the modulus remains virtually constant across temperature changes, making it suitable for applications like springs and hairsprings where insensitivity to variations in elastic force is required.
- Invar: Focuses on dimensional stability (invariability of length)-it has an extremely low coefficient of thermal expansion (~1.2×10⁻⁶/℃), making it suitable for applications like length standards and LNG storage tanks where insensitivity to thermal expansion and contraction is required.
It is common to confuse these two materials during procurement, but there is a strict distinction regarding where they are actually used.
Machining and Welding
The properties of Elinvar are achieved through heat treatment rather than being inherent upon manufacture; without aging, there is no constant elasticity-this is the fundamental principle of Elinvar processing. Key performance characteristics, such as constant elasticity and strength, depend heavily on the final heat treatment (aging) process, and users must strictly adhere to the required heat treatment procedures based on component design specifications.
Three-step heat treatment process-all steps are essential:
Solution annealing (830–900°C)
Cold forming (performed while the material is in the solution-annealed/soft state)
Age hardening (approx. 600–700°C for several hours; specific parameters depend on the grade)
1. Cold working: Elinvar is typically supplied in the solution-annealed (soft) state, with cold forming performed by the customer. While the material possesses good ductility, it has a high work-hardening rate; therefore, stress-relief annealing (500–600°C) is required after forming to eliminate internal stresses. Adequate cooling and lubrication are necessary for sheet metal stamping and bending operations.
2. Welding/Brazing: Welding performance is superior in the solution-annealed state; weldability decreases after age hardening.
3. Machining/Grinding: Precision machining should ideally be completed in the solution-annealed state. Post-aging, the material hardens significantly (~35–45 HRC), making subsequent machining operations very difficult.
For more information, please contact:
Email: susan@lorkgroup.com
WhatsApp: +86 19937075488
Chemical Composition
Over a century of development, Elinvar alloys have evolved into various commercial grades, with core composition ranges as follows:
Typical chemical composition (mass fraction, wt%):
| element | Content Range |
| Ni | 33-36% |
| C | 0.5-2.0% |
| Cr | 4-12% |
| W | 1-3% |
| Si | 0.3-2.0% |
| Mn | 0.45-2.4% |
| Ti | Approximately 2–3% (age-hardenable types only) |
| Fe | Margin |
Key Point: Carbon (c) content is the critical factor enabling the industrial mass production of Elinvar. Early production required extremely precise control over smelting composition; stable, large-scale manufacturing was only achieved later by adjusting the carbon content and introducing dispersed M7C3 carbides precipitated during tempering. This distinguishes it from other precision elastic alloys in terms of industrial value.
Mechanical Properties
| Material | Grade 1 Requirements |
| Tensile Strength | 1250 MPa |
| Yield Strength (0.2%) | 1150 MPa |
| Temperature coefficient of the modulus of elasticity | -3 × 10⁻⁶/℃ ~ +3 × 10⁻⁶/℃ |
| Modulus of elasticity | 177-183 GPa |
| Density | 8.0-8.2 g/cm³ |
| Hardness (aged condition) | ~ 35-45 HRC |
Note: Elinvar is typically supplied in the solution-annealed (soft) state; customers generally perform the aging treatment themselves after stamping or forming. While the elastic modulus is already constant in the soft state, the strength is only about one-third of that in the aged state. A common pitfall is that many customers are unaware that aging is required to achieve the nominal yield strength of 1150 MPa; installing the material directly in its solution-annealed state leads to spring deformation.
Technical Consultation Prior to Quotation
We have compiled a summary of key technical parameters regarding Elinvar Alloy-points frequently discussed during past inquiries and procurement orders-to facilitate rapid quotation.
Dimensions/Specifications: Strip thickness (typically 0.05–5 mm) and width; wire diameter.
Delivery Condition: Solution-annealed (soft state, requiring customer-performed aging) or aged (finished hard state)? - This is the most frequently overlooked detail.
Aging Requirements: If purchasing in the solution-annealed state, does the customer have their own aging furnace? Is an aging process package required from us?
Surface Requirements: Bright Annealed (BA), bright cold-rolled, etc., to meet optical inspection or high-finish assembly requirements.
Other Requirements: Are special tolerances, edge passivation, or chamfering required? Is an MTC (Material Test Certificate) required?
Recommendations for material condition selection:
If you need to perform your own stamping or spring winding → Solution-treated condition (soft, easy to process); perform aging treatment yourself after forming.
If using the finished product directly → Aged condition (hard, already possesses the designed performance properties).
For customers without heat treatment capabilities → You must purchase finished products in the aged condition; otherwise, the strength of the solution-treated material will be only one-third that of the aged material, and it will not harden even if processed.
Note: The aging process for Elinvar is essential for ensuring performance; without it, even the highest-quality raw material will fail to deliver the desired results. No aging means no constant elasticity. If you lack heat-treatment facilities, simply source the material in its aged, finished state. The failure mode is straightforward: springs that haven't undergone aging are too soft-they either deform immediately upon installation or lose their spring force after a short period of operation. Some of our customers have overlooked this point, resulting in a finished product lifespan that was only one-fifth of the rated value.
Hot Tags: elinvar alloy | lork, China elinvar alloy | lork manufacturers, factory
You Might Also Like
Send Inquiry