COMPREHENSIVE TECHNICAL ANALYSIS AND DATASHEET OF UNS C17200 BERYLLIUM COPPER FASTENERS
UNS C17200, globally recognized as Alloy 25, is the undisputed heavyweight champion of the copper alloy family. By alloying copper with 1.80% to 2.00% Beryllium and subjecting it to rigorous precipitation-hardening (age-hardening) thermal treatments, the material undergoes a radical metallurgical transformation. The resulting fasteners possess tensile and yield strengths rivaling those of high-strength alloy steels, completely shattering the traditional limitations of copper hardware.
Beyond its staggering mechanical strength (capable of exceeding 175,000 psi), C17200 Beryllium Copper provides a highly unique triad of engineering properties: it is entirely non-magnetic, strictly non-sparking, and highly resistant to cryogenic embrittlement. This makes Alloy 25 fasteners the critical choice for explosive oil & gas environments, MRI medical equipment, and aerospace applications where using standard high-strength steel is impossible or dangerous.
■ Product Overview & Specifications
| Material Classification | Precipitation-Hardened Beryllium Copper (Alloy 25) |
|---|---|
| UNS Designation | C17200 |
| Microstructure | Alpha Copper Matrix with Gamma Phase (Beryllium) Precipitates |
| Magnetic State | Completely Non-Magnetic (Safe for MRI / Directional Drilling) |
| Density | 8.25 g/cm³ (0.298 lb/in³) |
| Size Range | Metric: M3 to M48 | Imperial: #4 to 2" |
| Primary Attribute | Highest Tensile Strength of any Copper Alloy (Non-Sparking) |
■ Proprietary Datasheet Download (GATED)
UNS C17200 Beryllium Copper — Complete Technical Datasheet
Contains highly detailed heat-treatment temperature curves (AT vs. HT tempers), extreme cryogenic fatigue limits, and certified non-sparking impact data for ATEX-regulated assembly zones.
⬇ DOWNLOAD DATASHEET■ MTC Integration Section
Because C17200 relies entirely on precise thermal treatment to achieve its steel-like strength, verification of the final temper is a zero-compromise requirement for high-load applications.
- EN 10204 Type 3.1: Provides exact Beryllium content, verifiable thermal aging (precipitation) profiles, and physical Rockwell hardness test results proving the material reached the required HT (TH04) specification.
- EN 10204 Type 3.2: Often mandated for deep-water directional drilling (MWD/LWD) components, requiring third-party ultrasonic and magnetic permeability testing.
■ Chemical Composition
The strength of C17200 is driven by its ~2% Beryllium content. Minor additions of Cobalt and Nickel are carefully controlled to inhibit grain growth during the high-temperature solution-annealing phase, ensuring a highly uniform, fine-grained microstructure prior to age-hardening.
| Beryllium (Be) | Cobalt (Co) + Nickel (Ni) | Co + Ni + Iron (Fe) | Silicon (Si) | Aluminum (Al) | Copper (Cu) |
|---|---|---|---|---|---|
| 1.80 – 2.00 | 0.20 Min | 0.60 Max | 0.20 Max | 0.20 Max | Balance |
■ Mechanical Properties
| Mechanical Property | TH04 Temper (Hard Drawn & Age Hardened) |
|---|---|
| Tensile Strength | 165,000 - 200,000 psi (1140 - 1380 MPa) |
| Yield Strength (0.2% Offset) | 145,000 - 175,000 psi (1000 - 1210 MPa) |
| Hardness (Rockwell C) | 36 - 42 HRC |
| Electrical Conductivity | 17% - 22% IACS @ 20°C |
■ Equivalent Grades & Designations
| Standard / System | Designation |
|---|---|
| ASTM Specifications | ASTM B196 (Rod & Bar), ASTM F467 / F468 (Fasteners) |
| Common Trade Names | Alloy 25, BeCu, Berylco 25, Moldmax High Strength |
| European Equivalent | EN CW101C / CuBe2 (DIN 2.1247) |
| Military / Aerospace | AMS 4533, MIL-C-21657 |
■ Applications & Industries
- Oil, Gas & Mining (ATEX Zones): High-strength non-sparking safety tools, flange bolts, and structural fasteners in explosive methane or combustible dust environments.
- Medical & Scientific Imaging: Structural assembly hardware for MRI machines and NMR spectrometers requiring strictly non-magnetic components (magnetic permeability near 1.000).
- Aerospace & Deep Sea: Cryogenic valve fasteners, deep-water wellhead hardware, and directional drilling (MWD) housings requiring steel-like fatigue limits without iron-based corrosion.
■ Compatible Fastener Assemblies
| Mating Bolts/Studs | Internal Threads (Nuts) | Washers |
|---|---|---|
| C17200 Hex Bolts & Socket Cap Screws | C17200 Heavy Hex Nuts | C17200 Flat & Belleville Washers |
■ Torque & Installation Guidelines
Unlike standard pure coppers or bronzes, C17200 in the TH04 (Age Hardened) condition behaves mechanically like a high-strength alloy steel (comparable to Grade 8). However, because the surface is still copper-based, extreme clamping forces can lead to severe thread galling. High-pressure anti-seize lubricants (e.g., Moly or Graphite-based) are highly recommended.
| Nominal Diameter | Threads Per Inch (UNC) | Target Torque — Lubricated (ft-lbs) |
|---|---|---|
| 1/4" | 20 | 9 - 11 |
| 3/8" | 16 | 30 - 35 |
| 1/2" | 13 | 80 - 90 |
| 3/4" | 10 | 250 - 280 |
■ Frequently Asked Questions
1. How does a copper alloy get as strong as steel?
Through a process called precipitation hardening. Initially, the Beryllium is dissolved fully into the copper matrix (solution annealed), leaving the metal soft and workable. After the fasteners are machined, they are baked at a precise temperature (~600°F / 315°C) for several hours. This causes the Beryllium to precipitate out of the solid solution on a microscopic level, creating a dense network of interlocking crystals that violently resist deformation, skyrocketing the tensile strength to nearly 200,000 psi.
2. Is Beryllium Copper safe to handle?
Yes, C17200 fasteners in their final solid state are completely safe to handle, install, and use. The health risk associated with Beryllium (a respiratory disease called Berylliosis) only occurs if Beryllium dust, fumes, or micro-particles are inhaled. Therefore, strict industrial safety controls are only required during the manufacturing phases (grinding, welding, or high-speed dry machining) of the alloy.
3. What does "Non-Sparking" truly mean in hazardous environments?
In explosive environments (like oil rigs or grain silos), dropping a standard steel bolt or striking a steel wrench can generate a high-temperature "mechanical spark" capable of igniting ambient gases. Beryllium Copper alloys do not generate these mechanical sparks upon impact, making them ATEX-compliant and mandatory for safety-critical hardware in combustible zones.