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Alloy Technical Data Sheet
C17200 Beryllium Copper
Age-Hardenable Copper Alloy (Berylco® 25) · UNS C17200
The highest-strength copper alloy — age-hardenable beryllium copper combining spring strength with good electrical and thermal conductivity.
General Properties
C17200 (Berylco® 25 / Alloy 25) beryllium copper reaches the highest strength and hardness of any commercial copper alloy while keeping useful electrical and thermal conductivity. Strip is supplied in age-hardenable tempers, which are formed and then heat treated to full strength, or in mill hardened tempers, which are heat treated by the mill and ready to form and use as supplied.
It offers excellent spring properties, fatigue strength and resistance to stress relaxation, and is non-magnetic and non-sparking. Typical uses include electrical contacts and connectors, precision springs, switch and relay parts, EMI/RFI shielding and non-sparking components.
Chemical Composition
| Element | C17200 |
|---|---|
| Beryllium | 1.80–2.00 |
| Nickel + Cobalt | 0.20 min. |
| Nickel + Cobalt + Iron | 0.60 max. |
| Copper + Be + Ni + Co + Fe | 99.5 min. |
Temper Designations
Berylco® 25 strip is supplied in three groups of tempers. Each temper has an ASTM designation and a common name.
- Age-hardenable tempers — TB00 (A), TD01 (¼H), TD02 (½H), TD04 (H). Formed or stamped first, then heat treated, which roughly doubles the strength.
- Heat treated tempers — TF00 (AT), TH01 (¼HT), TH02 (½HT), TH04 (HT). The strength reached after the matching age-hardenable temper is given the producer’s recommended heat treatment.
- Mill hardened tempers — TM00 (AM), TM01 (¼HM), TM02 (½HM), TM04 (HM), TM05 (SHM), TM06 (XHM), TM08 (XHMS). Heat treated by the mill to a strength between the age-hardenable and heat treated tempers, and usually formed and used as supplied.
Mechanical Properties
| Temper | Heat treat | Tensile, ksi | Yield, ksi | Elong., % | Rockwell |
|---|---|---|---|---|---|
| TB00 (A) | None | 60–78 | 28–60 | 35–65 | B45–78 |
| TD01 (¼H) | None | 75–88 | 60–80 | 15–40 | B68–90 |
| TD02 (½H) | None | 85–100 | 75–95 | 9–30 | B88–96 |
| TD04 (H) | None | 100–130 | 90–112 | 2–18 | B96–104 |
| TF00 (AT) | 600 °F/3 hr | 165–195 | 140–175 | 3–15 | C36 min. |
| TH01 (¼HT) | 600 °F/2 hr | 175–205 | 150–185 | 3–10 | C36 min. |
| TH02 (½HT) | 600 °F/2 hr | 185–215 | 160–195 | 1–8 | C38 min. |
| TH04 (HT) | 600 °F/2 hr | 190–220 | 165–205 | 1–6 | C38 min. |
| TM00 (AM) | Mill | 100 min. | 70–95 | 16–30 | B95 min. |
| TM01 (¼HM) | Mill | 110 min. | 80–110 | 15–25 | C20 min. |
| TM02 (½HM) | Mill | 120 min. | 95–125 | 12–22 | C23 min. |
| TM04 (HM) | Mill | 135 min. | 110–135 | 9–20 | C28 min. |
| TM05 (SHM) | Mill | 150 min. | 125–140 | 9–18 | C31 min. |
| TM06 (XHM) | Mill | 155 min. | 135–165 | 4–15 | C32 min. |
| TM08 (XHMS) | Mill | 175 min. | 150–180 | 3–12 | C33 min. |
Ranges and minimums as published by NGK Metals for Berylco® 25 strip. Yield is 0.2% offset; elongation is in 2″. Heat treated (TF00/TH) values apply after the heat treatment shown. Mill = mill hardened.
Heat Treatment
NGK Metals lists 600 °F (315 °C) for 3 hours to bring TB00 (A) to TF00 (AT), and 600 °F for 2 hours to bring TD01, TD02 and TD04 to TH01, TH02 and TH04. Mill hardened (TM) tempers are already heat treated by the mill. Follow the producer’s recommendations for your application.
Physical Properties
| Density | 0.298 lb/in³ (8.25 g/cm³) |
|---|---|
| Modulus of elasticity | 18.5 × 10⁶ psi (128 GPa) |
| Electrical conductivity | 22% IACS |
| Thermal conductivity | 60 Btu/hr·ft·°F (104 W/m·K) |
| Thermal expansion, 68–390 °F | 9.7 × 10⁻⁶ in/in/°F (17.5 × 10⁻⁶ cm/cm/°C) |
| Specific heat | 0.10 Btu/lb·°F (420 J/kg·K) |
| Magnetic | Non-magnetic |
Typical values at 68 °F, as published by NGK Metals.
Safe Handling
Beryllium copper in solid form poses no known health risk. Operations that create airborne dust, fumes or mist — such as grinding, welding or machining without coolant — require appropriate controls. Refer to the producer’s Safety Data Sheet (SDS) for handling guidance.
Values are typical or specification minimums as noted, provided for information only, and should not be used as design limits or as a guarantee of properties for any particular lot or application. Certified test reports are supplied with each order. Berylco® is a registered trademark of NGK Metals.Rev. 10/2026