CuBe2 Strip Properties: Strength, Hardness and Elasticity

CuBe2 strip — graded as EN CW101C, DIN 2.1247, UNS C17200, or Alloy 25 — is a precipitation-hardening copper beryllium alloy that delivers tensile strength up to 1,320 MPa alongside 22–25% IACS electrical conductivity. Few copper alloys match this combination. For precision stamping facilities producing connector terminals, relay blades, or battery spring contacts, understanding the strength, hardness, and elasticity of CuBe2 strip is not academic — it directly controls whether your tooling runs clean or your line stops for a die adjustment.

Understanding CuBe2 Strip: Composition and Key Characteristics

Your engineering team needs to know exactly what they are working with in terms of chemistry and mechanics before they specify any temper or place a trial order. The numbers must match what you drew; they can't be close.

Chemical Composition: Two Standards, Two Sets of Limits

There are two separate processes that run CuBe2 strip, and mixing them up leads to real procurement mistakes. According to DIN EN 1654 (grade CW101C / 2.1247), the beryllium content is 1.80 to 2.00 percent, and the maximum for Co+Ni+Fe is 0.60 percent. Under ASTM B194 / B196 (C17200), the beryllium range is 1.80–2.00%, and the maximum for Co+Ni+Fe is also 0.60%. The two standards are aligned on these upper limits. In both cases, Co+Ni must be at least 0.20%. Any good process engineer will notice right away if you write the wrong upper limit on a material datasheet, like listing 0.50% for a customer who follows ASTM standards. This will hurt your credibility as a supplier.

Grade Equivalents and Applicable Standards

CuBe2 strip has different grade names in different areas, such as EN CW101C, DIN 2.1247, UNS C17200, Alloy 25, and RWMA Class 4. Standards like DIN EN 1654, ASTM B194, and ISO 5182 are in charge. All production batches should be certified to EN 10204 3.1, which makes it possible to track chemical and mechanical test results down to the batch level. The quality systems must be certified by ISO 9001:2015, and all of the materials used must be RoHS compliant.

Available Forms, Sizes, and Temper Conditions

You can get CuBe2 strip in thicknesses from 0.05 mm to 3.0 mm and widths up to 300 mm. It comes in precision-slit coils or cut strips. There are three types of tempers: annealed soft temper (R200 / TB00) for complex deep-draw stamping and then aging in-house; cold-rolled spring tempers (R410, R510, and higher) for direct-to-press use; and fully aged condition (H / TH04) where the best properties are already present. Picking the right temper during the order process is what keeps the die from having to be re-tuned after the material changes.

Strength of CuBe2 Strip: Mechanisms and Performance

Precipitation hardening gives CuBe2 strip its strength. This is a controlled aging heat treatment that makes beryllide particles form inside the copper matrix, making it much less likely to bend or bend out of shape. This isn't just treating the surface; it changes the whole cross-section.

Tensile Strength After Aging

CuBe2 strip has a tensile strength of 1,110–1,320 MPa after being heated at about 315 °C for two to three hours. It can hold the same amount of weight as many high-grade spring steels, but it still has non-ferrous qualities like not rusting and not being magnetic. This tensile ceiling is more important than peak hardness for connector terminals that need to keep their contact force over thousands of mating cycles.

Yield Strength and Elastic Limit

The yield strength for aged CuBe2 strip is between 950 and 1,210 MPa. A high yield-to-tensile ratio means that the material doesn't permanently set when it's under load for a long time. This is exactly what designers of battery contacts and relay blades need. When a spring element bends and needs to return to its original shape, the yield strength tells us if it does.

Stress Relaxation Resistance vs. Alternative Alloys

Over long hold times, CuBe2 strip keeps more than 90% of its initial stress at 150 °C. Phosphor bronze, on the other hand, generally shows significant stress relaxation above 100 °C and is less suitable for applications requiring stable contact pressure at elevated temperatures. This retention information should be on the MTC, not just in a product brochure, for automotive electronics and EV battery contacts that work in hot places.

Hardness of CuBe2 Strip: Measurement and Industrial Relevance

Hardness controls die wear, burr formation, and surface integrity during stamping. It also determines whether a finished spring contact will resist indentation under repeated mechanical loading in service.

Hardness Scales and Aged Values

Aged CuBe2 strip tests at 36–42 HRC (Rockwell C) or 350–420 HV (Vickers). Rockwell C is the practical scale for incoming inspection in most stamping shops. Vickers testing — conducted per ASTM E92 — is preferred for thin-strip QC because the indenter load can be scaled down for sub-0.2 mm material without cracking the sample.

How Temper State Changes Hardness

Soft-tempered (R200 / TB00) CuBe2 strip arrives in a ductile, formable condition — hardness is low by design, allowing complex bending without cracking. Cold-rolled spring tempers (R410 through R1200 in EN notation, TD02 through TM04 in ASTM notation) introduce work hardening progressively. The engineer's job is to select the temper that reaches target hardness after your specific post-stamp aging cycle, not before. Batch-to-batch hardness drift of more than ±2 HRC typically triggers springback inconsistency at the press, which is why MTC data must be reviewed for every incoming coil.

Hardness and Die Wear at the Press

Stamp shop floor experience consistently shows that burr formation and premature die wear correlate with two causes: incorrect hardness specification for the die geometry, and strip edge quality. CuBe2 strip produced to tight slit tolerances — with clean, burr-free edges and thickness tolerance as tight as ±0.005 mm — significantly extends die life compared to strip with ragged slit edges.

Elasticity of CuBe2 Strip: Flexibility and Resilience in Use

Elasticity is a measure of how much a material changes shape when it is loaded and how well it returns to its original shape when the load is taken away. Elastic recovery is not just a number on a datasheet for spring contacts and relay blades; it is the functional metric.

Elastic Modulus of CuBe2 Strip

CuBe2 strip has an elastic stiffness of about 131 GPa, which is much higher than phosphor bronze (about 110 GPa) and brass (about 97 GPa). A higher modulus means that the spring element can hold more force per unit of movement. This is helpful when designers have to work with very small cross-sections to meet contact force goals because connectors are getting smaller.

Fatigue Strength Under Cyclic Loading

CuBe2 strip is better at resisting cycle bending at high frequencies. The contact spring may be used in relay blades and microswitches for millions of cycles over the course of its life. The material's fatigue strength, which is supported by its high yield and work-hardened matrix, lets it handle these cycles without cracks starting to form in stages at the bend radius. Depending on the temper, designers usually set a minimum bend radius of 1×t to 2×t. This should be checked against your specific forming geometry during trial stamping.

Elastic Recovery in Connector Terminal Design

The ability of the CuBe2 strip to bounce back to its original shape after being bent is what keeps the entry force and contact resistance fixed over the product's entire service life. Stress relaxing data taken at 150 °C can directly tell you how much of the spring's memory will still be there after being heated up and used. Before you finalize your material specifications, ask any CuBe2 strip supplier for this information.

How to Select the Right CuBe2 Strip for Your Project

Before ordering a kilogram of CuBe2 strip, you need to check the heat, thickness tolerance, and paperwork standards to make sure it will work for your needs.

Matching Temper to Your Process

The right temper is determined by your production process. If the shapes your dies make are complicated, like deep draws, tight radii, or many bends, start with annealed R200 (TB00) and age it in-house after shaping. You don't have to heat treat the material after it's been formed if you use cold-rolled spring tempers R410–R750. These give you direct-use mechanical qualities. When you order pre-hardened strip and then try to carry out additional heavy forming operations, you risk reducing its fatigue life and should avoid this approach unless the forming requirements have been verified.

Verifying Documentation Before Ordering

Every batch of CuBe2 strip should come with an EN 10204 3.1 Mill Test Certificate that lists the correct composition (with Be and Co+Ni+Fe both stated clearly), as well as the hardness, tensile strength, yield strength, and electrical conductivity. If your downstream customer needs stress relaxation or fatigue data for BOM approval, ask for it in writing before the trial sample stage, not after you've committed to tools.

Evaluating Supplier Capability and Safety Documentation

A good CuBe2 strip supplier should have slit tolerances of ±0.005 mm on thickness, clean-edge coils with no visible burr at 10x magnification, coil weights that are right for your press feed capacity, and a current Safety Data Sheet (SDS) that talks about how to control beryllium dust exposure. Your workplace health team needs the SDS before production begins so that it can review the handling, storage, and exposure-control requirements. This is a legal requirement in many jurisdictions.

Conclusion

CuBe2 strip is used for precision spring and connector stamping because it has certain properties that can be measured. Its tensile strength can reach 1,320 MPa after aging, its hardness can reach 42 HRC, its elastic modulus can reach 131 GPa, and its stress relaxation retention can go above 90% at 150 °C. These numbers, along with the fact that this alloy has an IACS conductivity of 22–25%, explain why it is named on so many drawings of connectors and relays. To have a successful material program, you need to make sure you use the right temper for your process, demand batch-level MTC documentation to the right standard (EN or ASTM, not both), and check the quality of the edges and thickness of the trial coil before it gets to your press.

FAQ

1.What is the difference between CuBe2 strip in EN and ASTM specification?

The limits are effectively aligned. Both EN 1654 CW101C and ASTM B194/B196 C17200 specify Be 1.80–2.00% and Co+Ni+Fe 0.60% max (with Co+Ni ≥0.20%). Always confirm the exact standard revision on your drawing, but for strip, the chemical windows are practically the same.

2.Can CuBe2 strip be stamped in the annealed state and then hardened?

Yes. Annealed temper (R200 / TB00) is specifically intended for complex forming. After stamping, age at approximately 315 °C for 2–3 hours to reach peak tensile and hardness values. This is the standard production path for deep-drawn contacts and spring elements.

3.How does CuBe2 strip compare to phosphor bronze for stress relaxation?

CuBe2 strip retains over 90% of its initial stress at 150 °C. Phosphor bronze shows significant stress relaxation above 100 °C and is not suitable for elevated-temperature connector or relay applications where long-term contact pressure stability is required.

4.What safety measures apply when stamping CuBe2 strip?

Beryllium-containing dust generated during stamping, grinding, or sawing is a regulated occupational health hazard. Your facility must implement engineering controls (local exhaust ventilation), provide appropriate PPE, conduct air monitoring, and maintain a current SDS on file. Solid strip handling does not present the same risk.

5.What minimum order quantities are available for trial purposes?

Trial quantities of 10–100 kg are available for temper confirmation and die validation runs, with standard stock items dispatched within 3–5 days and custom slit orders delivered in 15–20 days.

Source Your CuBe2 Strip from JYDS — Request a Quote Today

JYDS has been making specialized beryllium copper for more than 25 years and brings that experience to every order. We have over 500 tons of stock, do our own vacuum induction melting to make sure the metal is consistent, and make sure that every batch of CuBe2 strip meets all the requirements of EN 10204 3.1. We sell it directly from the maker at a fair price. Items in stock will be sent out in 3–5 days, and custom-slit coils will be sent out in 15–20 days. Questions about technology get answers from our team within two hours. You can email us at js01@jstongcai.com.cn to get an official quote or a trial example.

References

1. European Committee for Standardization. DIN EN 1654: Copper and Copper Alloys — Strip for Springs and Connectors. CEN, 2012.

2. ASTM International. ASTM B194: Standard Specification for Copper-Beryllium Alloy Plate, Sheet, Strip, and Rolled Bar. ASTM International, 2021.

3. ASTM International. ASTM B196/B196M: Standard Specification for Copper-Beryllium Alloy Rod and Bar. ASTM International, 2021.

4. Copper Development Association. Beryllium Copper Alloys: Properties, Processing and Applications. CDA Publication No. 109, 2000.

5. Davis, J.R. (Ed.). Copper and Copper Alloys. ASM International, 2001.

6. International Organization for Standardization. ISO 5182: Copper and Copper Alloys — Composition of Master Alloys. ISO, 2016.