Springs & connectors
High-cycle electrical contacts, current-carrying springs, connector contacts. The conductivity + strength + fatigue combination is unique.
Cu-Be precipitation-hardening alloy · UNS C17200
Beryllium Copper C172
The strongest copper alloy — UTS 1310 MPa after age hardening. Combines the conductivity of copper with the strength of steel. Standard for springs, electrical connectors, EDM electrodes, oil & gas downhole tools, and non-sparking tools where its safety property matters.
UTS (aged)
1310 MPa
Density
8.36 g/cc
Cond.
22% IACS
Mach.
40 /100
Health hazard
Beryllium dust and fumes are extremely hazardous — chronic inhalation causes chronic beryllium disease (CBD), a serious irreversible lung condition. Solid BeCu is safe to handle, but machining, grinding, and welding generate harmful particulates. We machine BeCu under controlled ventilation with dedicated equipment and HEPA collection.
When to use
Pick BeCu for the impossible combination.
Beryllium copper is the only commercial alloy that combines high strength (1300+ MPa), high conductivity (22% IACS), excellent fatigue, and non-sparking behavior. It’s precipitation-hardened by aging at ~315 °C — solution-anneal soft, machine, then age to peak hardness.
Three primary applications drive most BeCu work: springs and electrical contacts (where the conductivity + strength + fatigue combination is unique), EDM electrodes (combining conductivity, strength, and machinability), and non-sparking tools for use around explosives or flammable atmospheres. Each application benefits from a specific temper.
Strengths
Why nothing else works.
- Strongest copper alloyUTS 1310 MPa aged — same range as 17-4PH stainless. No other copper alloy comes close.
- High conductivity22% IACS — much higher than steel, lower than pure copper. Combined with strength, unique.
- Outstanding fatigueEndurance limit ~280 MPa. The spring alloy of choice for high-cycle applications.
- Non-sparkingWon't generate sparks on impact — required in explosive-atmosphere tooling (gas plants, ordnance).
- Non-magneticDiamagnetic. Used in instruments and sensors where magnetic interference is unacceptable.
- Cryogenic capableMaintains ductility at liquid-helium temperatures. Used in superconducting magnet hardware.
Trade-offs
What you accept.
- Beryllium dust hazardInhaled particulates cause CBD. Machining requires controlled environment, HEPA collection, and operator monitoring. Real ongoing cost.
- High cost$50–90/lb stock. Multiples of brass; multiples of stainless. Justified only where the property combination is required.
- Density penalty8.36 g/cc — slightly less than copper, similar to stainless. No weight savings.
- RoHS / regulatoryBeryllium is restricted in EU consumer electronics. Industrial and medical applications retain exemptions but watch contract clauses.
- Aging schedule mattersFinal properties depend on aging temp + time. Specify both — different aging schedules trade strength vs ductility.
- DisposalChips and scrap are regulated waste. Must go to certified recycler — can't drop in normal copper bin.
Specs
Mechanical, physical & chemical data.
Properties shown for solution-treated and aged condition (TH04 / HT) — the standard high-strength temper. Solution-annealed (A) values are roughly 1/4 of these.
Mechanical
Properties (TH04 — aged)
| Ultimate tensile strength | 1310 MPa (190 ksi) |
|---|---|
| Yield strength (0.2% offset) | 1100 MPa (160 ksi) |
| Elongation at break | 5% |
| Modulus of elasticity | 131 GPa |
| Hardness (TH04) | 36-42 HRC |
| Hardness (annealed) | 45–78 HRB |
| Endurance limit 10⁸ cycles | 275 MPa |
| Compressive yield | 1100 MPa |
Source: Materion datasheet. Annealed (A) condition: UTS 415 MPa, YS 240 MPa, elongation 35%. The aging step is the strength source.
Physical & thermal
At room temperature
| Density | 8.36 g/cc (0.302 lb/in³) |
|---|---|
| Melting range | 865 – 980 °C |
| Specific heat | 0.420 J/g·°C |
| Thermal conductivity | 105 W/m·K |
| CTE (20–200 °C) | 17.0 µm/m·°C |
| Electrical conductivity | 22% IACS |
| Magnetic permeability Non-magnetic | Diamagnetic |
| Solution treat temp | 780 °C |
Conductivity 22% IACS is much higher than steel (3-7%) but lower than pure copper (100%). The strength makes up for the conductivity penalty in spring contacts.
Composition
Chemistry, weight %
| Copper (Cu) | balance (~97.5%) |
|---|---|
| Beryllium (Be) | 1.80 – 2.00 |
| Cobalt + Nickel (Co + Ni) | 0.20 – 0.6 |
| Iron + Nickel + Aluminum + Silicon Total impurities | 0.6 max |
The 1.8-2.0% Be is the precipitation-strengthening element. Less Be (C17500, 0.4-0.7%) trades strength for higher conductivity.
Specifications
Common purchase specs.
AMS 4533
Bar, rod — TF00 (formerly AT), solution + precipitation heat treated
AMS 4534
Bar, rod — TH04 (formerly HT), solution treated + cold worked + aged
AMS 4535
Mechanical tubing — TF00 (formerly AT)
ASTM B196
Rod, bar, wire — Cu-Be
ASTM B194
Sheet, strip, plate
MIL-C-21657
Forgings — Cu-Be
UNS C17200 / CDA 172
Standard designations
Machining
How we cut it.
Always machine in solution-annealed (A) condition — easy to cut, similar to brass. Age-harden after machining to lock in final strength. Critical: dust collection. We run BeCu only on dedicated machines with HEPA filtration.
Cutting speed (annealed)
200–400 SFM with carbide. Slower than brass — chips are tougher.
Feed rate
Aggressive constant feed. BeCu doesn't work-harden meaningfully in annealed state.
Tooling
Polished or coated carbide. Sharp positive rake.
Coolant
Flood with water-soluble. Critical for chip removal AND dust suppression.
Dust control
HEPA-filtered local exhaust mandatory. Operator wears PAPR or N100 respirator on roughing ops.
No grinding (without precaution)
Dry grinding generates the worst dust. Wet grind only, with full ventilation.
Aging schedule
Standard: 315 °C × 3 hr in air. Hold dimensions on critical features — age hardening contracts the part slightly (volume shrinks, on the order of ~0.0005″/inch).
Chip handling
Chips go to certified beryllium-waste recycler. NOT in normal scrap copper.
Applications
Where BeCu earns the cost and complexity.
EDM electrodes
Combination of conductivity, strength, and machinability makes BeCu a top electrode for sinker EDM — especially fine-detail mold work.
Non-sparking tools
Hammers, wrenches, pry bars used around explosive atmospheres (oil refineries, ordnance plants, gas distribution). Won't strike sparks.
Compare
Related materials.
Higher conductivity
C110 Copper →
100% IACS — when conductivity matters more than strength or fatigue.
Same strength + cheaper
17-4PH →
Same UTS range. ~1/4 the cost. Use when conductivity isn't required.
Bearing alternative
C932 Bronze →
For bushings — when the BeCu strength isn't required and bronze is enough.
Have a part that needs to be made right?
Tell us about your part and we'll quote within 24 hours. Aerospace, medical, and defense work welcome.
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