Beryllium copper C17200 – UNS C17200
Precipitation-hardening copper alloy (≈ 2% Be)
The strongest copper alloy: after aging it exceeds 1,200 MPa and about 38 – 42 HRC, while keeping electrical conductivity around 22% IACS. Combines high fatigue resistance, good corrosion resistance and the absence of sparking and magnetism. Supplied solution treated (soft, for machining and forming) or already hardened.
Designations and equivalents
| System | Designation |
|---|---|
| UNS | C17200 |
| W.Nr./EN | CW101C – CuBe2 |
| DIN | 2.1247 (CuBe2) |
| JIS | C1720 |
| Trade names | Alloy 25 (Materion), Berylco 25 (NGK), CuBe2 |
| Others | AMS 4533, 4534, 4650, 4651; MIL-C-21657; SAE J461/J463 |
Standards by product form
| Form | Standard |
|---|---|
| Bar | ASTM B196/B196M |
| Plate | ASTM B194 (plate, strip and rolled bar) |
| Forging | ASTM B570 (forgings and extrusions) |
| Wire | ASTM B197/B197M* |
Tolerances and HS codes
- Forged bars (round and square): machining allowance from 2 mm (Ø 6–16 mm) to 24 mm (Ø 400–500 mm) on the diameter. E.g. Ø 100–125 mm finished: +7 mm, tolerance +6 / −0 (length up to 3,500 mm).
- Forged discs: allowance of 4 to 9 mm on the diameter and 3 to 11 mm on the height, plus-only tolerance.
- Cutting and machining: band saw −0 / +5 to +15 mm on length; waterjet +10 % of thickness on the diameter (min. 2 mm); machined parts −0 / +2 to +5 mm on the diameter. See the full tables (INF 002 and INF 003, the same for every alloy).
| Form | NCM (Brazil, 8 digits) | HS (international, 6 digits) | HTS (USA, 10 digits)* | CN (European Union, 8 digits)* |
|---|---|---|---|---|
| Forged bar | 7407.29.10 | 7407.29 | 7407.29.5000 | 7407 29 00 |
| Hot-rolled bar | 7407.29.10 | 7407.29 | 7407.29.5000 | 7407 29 00 |
| Plate (> 10 mm, width ≥ 600 mm) | 7409.90.00 | 7409.90 | 7409.90.1030 | 7409 90 00 |
| Flange and fitting | 7412.20.00 | 7412.20 | 7412.20.0090 | 7412 20 00 |
Tariff class: other copper alloys (beryllium copper) (by chemical composition, under the Chapter 72 Notes and Section XV Note 5).
*: US and EU codes for reference. NCM per current legislation (General Rules of Interpretation, Notes to Chapters 72, 74 and 75 and Section XV Note 5). Confirm the final code with your customs broker according to the item size and finish. HS = first 6 digits of the NCM.
Chemical composition (%)
ASTM B196 / B194 (UNS C17200)
| Element | Range (%) |
|---|---|
| Be | 1.80 – 2.00 |
| Co + Ni | ≥ 0.20 |
| Co + Ni + Fe | ≤ 0.6 |
| Al | ≤ 0.20 |
| Si | ≤ 0.20 |
| Pb | ≤ 0.02 |
| Cu | balance (Cu + named elements ≥ 99.5) |
Mechanical properties
typical, bar (CDA)
| Property | Value |
|---|---|
| Solution treated (TB00): tensile strength | ≈ 495 MPa |
| Aged (TF00): tensile strength | ≈ 1,255 MPa |
| Aged (TF00): yield strength (0.2%) | ≈ 1,000 – 1,200 MPa |
| Aged (TF00): elongation | ≈ 3 – 4% |
| Cold worked and aged (TH04): tensile strength | ≈ 1,345 – 1,415 MPa |
| Hardness, aged (TF00 / TH04) | ≈ 39 – 42 HRC |
| Fatigue strength (10⁸ cycles, TF00) | ≈ 380 MPa |
Typical physical properties
| Property | Value |
|---|---|
| Density | 8.26 g/cm³ |
| Melting range | 866 – 982 °C |
| Modulus of elasticity | 128 GPa |
| Electrical conductivity (aged) | ≈ 22% IACS |
| Thermal conductivity (20 °C) | ≈ 107 – 130 W/m·K |
| Thermal expansion (20–300 °C) | 17.8 µm/m·K |
Heat treatment, welding and machining
| Item | Usual practice |
|---|---|
| Service temperature | Recommended up to ≈ 150 – 200 °C in continuous service under load; above that it loses strength by overaging and stress relaxation*. Keeps toughness at cryogenic temperatures. |
| Heat treatment | Solution treatment at ≈ 775 – 800 °C with water quench. Precipitation hardening at ≈ 315 °C for 2 – 3 h, air cooling. Hot working between ≈ 650 and 815 °C. Stress relief at ≈ 200 °C. |
| Welding | Good brazing and soft soldering on a clean surface. TIG/MIG and spot welding possible; the affected zone loses its hardening and the part must be heat treated again. Oxyacetylene welding not recommended. Caution: dry machining, grinding and sanding generate beryllium-containing dust; work with coolant and local exhaust. |
| Machining | Machines best in the aged, or solution treated and cold worked, condition; annealed it is gummy. Sharp carbide tool and abundant coolant. Caution: dry machining, grinding and sanding generate beryllium-containing dust; work with coolant and local exhaust. |
Typical applications
- Highly stressed springs, electrical contacts and connectors
- Non-sparking tools for explosive atmospheres
- Bushings and bearings for high loads (landing gear, heavy equipment)
- Plastic injection mold inserts with fast cooling
- Non-magnetic instrument and well-drilling components
- High-strength fasteners and Belleville washers
Alternatives: Low-beryllium copper C17510 when conductivity matters more than strength; chromium-zirconium copper C18150 for electrodes and conductive parts; nickel-aluminum bronze C63000 for beryllium-free bushings and non-sparking tools, with lower strength.
Frequently asked questions
What is the chemical composition of Beryllium copper C17200?
Per ASTM B196 / B194 (UNS C17200): Be 1.80 – 2.00; Co + Ni ≥ 0.20; Co + Ni + Fe ≤ 0.6; Al ≤ 0.20; Si ≤ 0.20; Pb ≤ 0.02.
Which standards cover Beryllium copper C17200?
Bar: ASTM B196/B196M. Plate: ASTM B194 (plate, strip and rolled bar). Forging: ASTM B570 (forgings and extrusions). Wire: ASTM B197/B197M*.
Up to what temperature can Beryllium copper C17200 be used?
Recommended up to ≈ 150 – 200 °C in continuous service under load; above that it loses strength by overaging and stress relaxation*. Keeps toughness at cryogenic temperatures.
Which materials can replace Beryllium copper C17200?
Low-beryllium copper C17510 when conductivity matters more than strength; chromium-zirconium copper C18150 for electrodes and conductive parts; nickel-aluminum bronze C63000 for beryllium-free bushings and non-sparking tools, with lower strength.
