Our alloys

C17200 (CuBe2 / Berylco 25): high-strength beryllium copper alloy

The Reference Beryllium Copper Alloy

The C17200 alloy, also known as CuBe2 (Berylco 25 or B25), is by far the most widely used alloy in the Berylco range — across all product forms: strip, rod, wire, and other items. It contains 2% beryllium in a copper matrix.

Properties

The C17200 alloy (Berylco 25 or B25) achieves the highest mechanical strength and hardness levels of any copper alloy after age hardening (up to 1500 MPa). C17200 (B25) is also available in the mill-hardened condition. Using the material in the mill-hardened temper eliminates the need for a subsequent age hardening heat treatment, removing the risk of distortion in finished parts and reducing production costs. The C17200 alloy (B25) offers unique combinations of mechanical and electrical properties, along with good formability in the annealed and lightly cold-worked conditions. It also stands out for its high fatigue strength and excellent stress relaxation resistance.

Equivalent Standards

StandardNumbering SystemDesignation
ASTMUNSC17200
ISO / AFNOR / DINISOCuBe2
BSENCW101C
NGKBerylcoBerylco 25 (B25)

Applications

Its unique combination of properties makes this alloy an essential material across a wide range of applications.

Aerospace & Defense. The high mechanical strength, fatigue resistance and non-magnetic behaviour of C17200 make it a reference material for connectors, contact springs, bearings and precision components in embedded systems. Its use is governed by AMS 4596 and AMS 4597 standards. Learn more about our aerospace solutions.

Electronics. C17200 strips and wires are widely used in the manufacture of electrical contacts, connectors and spring blades. The strength-conductivity combination meets the requirements of high-frequency and high-reliability components. Discover our electronics applications.

Energy & Oil and Gas. In pressurised or explosive environments, C17200 is used for valves, sensors and downhole equipment. Its non-sparking properties are a safety requirement in these contexts. See our energy applications.

Medical. The dimensional precision and mechanical strength of C17200 meet the requirements of surgical instruments, precision springs and non-magnetic implantable devices. Medical applications.

Automotive & Appliances. Contact springs, pressure sensors, injection components: C17200 is specified wherever long-term mechanical and electrical reliability is non-negotiable.

See all applications

Our Products

C17200 (B25) is available in all product forms: strip, rod, wire, plate, chill vents, and other items.

Why Choose NGK BERYLCO for C17200

Choosing NGK Berylco means choosing:

  • The European leader in beryllium copper alloys, with over fifty years of expertise.
  • A French manufacturer based in France, supported by local partners across Europe through its subsidiaries in Germany and the United Kingdom, and its long-established distributors in Italy, Spain, Poland, and Turkey.
  • A solid, reliable supplier belonging to a century-old industrial group, NGK Corporation, headquartered in Japan with a global presence.
  • A certified supplier, committed to product quality, environmental responsibility, and operator safety.

Beyond our technical expertise, choosing us means actively supporting French and European industrial sovereignty.

FAQ (Frequently Asked Questions)

The C17300 alloy (CuBe2Pb) is a lead-bearing variant of C17200. The addition of lead significantly increases the machinability rating to 60%, compared to approximately 20% for C17200 (CuBe2).
C17300 (Berylco 33/25) is available in rod form only, in various diameters (up to 28 mm), for screw-machining and turning applications.

C17200 is designated CuBe2 under the ISO standard. It is the same alloy, referred to differently depending on the standard used. In our product range, this alloy is Berylco 25 (abbreviated B25).

The conductivity of C17200 ranges from 15 to 23% IACS (International Annealed Copper Standard), depending on the temper condition — whether hardened, heat-treated, or as-rolled. Please refer to our catalog for the electrical conductivity values of our alloys by temper condition.

C17200 is non-magnetic, as are all Berylco beryllium copper alloys.

The C17200 alloy (Berylco 25) is available in approximately forty different temper conditions, as follows:

TemperMeaningDescription
AAnnealedSolution-annealed, soft condition. No cold work, no thickness reduction.
HHardCold-worked condition. Thickness reduced by 37% (maximum achievable). The harder the material, the more difficult it is to form.
1/2 HHalf HardCold-worked condition. Thickness reduced by 19%.
1/4 HQuarter HardCold-worked condition. Thickness reduced by 10%.
MMill-HardenedPre-aged under controlled conditions at the mill.
TTreatedAge-hardened condition, either at our facility or by the customer.
S
B		NGK-proprietary designationsSpecial tempers produced at our facility through controlled grain refinement, improving fatigue resistance and formability.

Tempers incorporating cold work, heat treatment, and high-formability mill-hardened conditions are available. The choice of temper will depend on the target properties and forming constraints.
Please refer to our catalog for the full range of temper conditions offered by NGK Berylco France. Our experts are available to advise you.