C17200 Beryllium Copper (Alloy 25): High-Strength Conductive Alloy for Springs & Tools
ASTM B194 / AMS 4533 · Published: 2026-06-01 · Updated: 2026-06-02
C17200 beryllium copper (Alloy 25) is a precipitation-hardening copper alloy containing 1.80-2.00% beryllium and 0.20% minimum cobalt, capable of achieving yield strengths exceeding 1,000 MPa while retaining electrical conductivity of 22% IACS —...
C17200 beryllium copper (Alloy 25) is a precipitation-hardening copper alloy containing 1.80-2.00% beryllium and 0.20% minimum cobalt, capable of achieving yield strengths exceeding 1,000 MPa while retaining electrical conductivity of 22% IACS — a combination unmatched by any other copper alloy. The age-hardening mechanism: beryllium precipitates from supersaturated solid solution as coherent Guinier-Preston zones and semi-coherent gamma-prime (CuBe) precipitates during aging at 315-345°C for 2-3 hours, providing approximately 4× increase in yield strength over the solution-annealed condition. The alloy is non-sparking and non-magnetic, making it the standard material for explosion-proof tools used in oil & gas, mining, and chemical plants.
Primary applications: non-sparking safety tools (wrenches, hammers, chisels), electrical switch blades and contact springs requiring both high conductivity and high fatigue strength, injection mold cores and cavity inserts for plastics processing (C17200's thermal conductivity of 105 W/m·K is 4× that of tool steel — significantly reducing mold cooling time), and aerospace bushings and bearings requiring high load capacity and corrosion resistance. Safety note: beryllium in particulate form (grinding dust, welding fume) is a Class 1 carcinogen (IARC Group 1). Machining, grinding, and welding of beryllium copper must be performed with adequate ventilation and particulate capture — the solid alloy is safe to handle.
Quick Facts
| Category | Copper Alloy |
| Standard | ASTM B194 / AMS 4533 |
| Density | 8250 kg/m³ |
| Yield Strength | 1,000-1,400 MPa (age-hardened) |
| Tensile Strength | 1,200-1,500 MPa |
Global Equivalents & Cross-Reference
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Frequently Asked Questions
Is beryllium copper dangerous to machine?
The solid alloy is safe to handle and machine. The hazard is from airborne beryllium particulates generated during grinding, sanding, or welding — inhalation of beryllium dust can cause chronic beryllium disease (CBD), a granulomatous lung condition. Machining operations that produce chips (turning, milling, drilling) are generally safe with standard coolant. Dry grinding, sanding, and welding require local exhaust ventilation and air monitoring per OSHA 29 CFR 1910.1024 (beryllium standard, PEL 0.2 μg/m³).
References & International Standards
- ASTM International. Standard Specifications for Steel & Metal Alloys. astm.org
- International Organization for Standardization (ISO). Metallic Materials — Cross-Reference Database. iso.org
- American Iron and Steel Institute (AISI). Steel Grade Designations & Equivalents. steel.org
- European Committee for Standardization (CEN). EN Steel Standards & Numbering System. cencenelec.eu