MetalsWhat is C18000 copper and what is it used for? Beryllium-free nickel-silicon-chromium copper
C18000 copper is nickel-silicon-chromium copper, beryllium-free. In this guide we explain what C18000 copper is, its composition, its properties, what it is used for and the sizes we stock.
What is C18000 copper?
C18000 copper (copper-nickel-silicon-chromium, CuNiSiCr) is a high-strength, heat-treatable alloy with good electrical and thermal conductivity and excellent resistance to softening at elevated temperatures. It is a beryllium-free RWMA Class 3 material, the benchmark for resistance welding electrodes and wheels, mold holders and components that combine mechanical strength and conductivity.
Chemical composition of C18000 copper
This is the typical composition of C18000 copper (UNS C18000 / RWMA Class 3 standard):
| Element | Contents | What for? |
|---|---|---|
| Nickel (Ni) | 1.80 – 3.00 % | Nickel: strength and hardenability |
| Silicon (Si) | 0.40 – 0.80 % | Silicon: forms hardening compounds |
| Chromium (Cr) | 0.10 – 0.80 % | Chromium: increases strength and hardness through precipitation |
| Iron (Fe) | 0.15 % max. | Iron, kept limited |
| Copper (Cu) | Balance | Base metal |
C18000 properties and treatment
C18000 (copper-nickel-silicon-chromium) is a high-strength alloy, hardenable by heat treatment, with good conductivity and excellent resistance to softening at high temperature. It is an RWMA Class 3, beryllium-free material, widely used in resistance welding electrodes and wheels, electrode holders and components that combine mechanical strength and conduction.
What is it for? Applications of C18000
C18000 copper is mainly used in:
- Resistance welding electrodes
- Welding wheels and tips
- Electrode holders and fixtures
- Sprue bushings
- Injection mold cavities
- Hot runner systems
- Mold inserts
- Contacts and switching
- High-temperature components
Forms and sizes we carry
At NAT MAC we stock C18000 copper in these forms and sizes:
| Package size | Sizes |
|---|---|
| Round bars | 1/2" – 4" (12.7 – 101.6 mm) |
| Plates | 1/8" – 6" (3.18 – 152.4 mm) |
If you need a particular size, tell us which one and we will gladly source it for you.
C18000 equivalents and standards
C18000 copper is also identified by these standards: UNS C18000 / RWMA Class 3. You can see how to read them in our article on metal standards.
In summary
- C18000 is nickel-silicon-chromium copper, beryllium-free (RWMA Class 3)
- High strength, good conductivity and resistance to softening at high temperature
- Ideal for electrodes, welding wheels and mold holders
- We carry it in round bars, plates, cut to size
Why buy your C18000 copper at NAT MAC?
We have more than 54 years of experience as an industrial supplier and ISO 9001 certified quality. We carry copper and its alloys, and we help you choose the right grade for your application.
- Quality C18000 copper, fully backed and traceable
- Material cut to the size you need
- Advice on choosing the right copper for your conductivity and strength needs
- Electrolytic copper and high-performance alloys
- On-time deliveries and competitive prices
Tell us what you'll make and what you need (conductivity, strength or weldability), and we'll recommend the right copper and form. Request your free quote.
Sources: data sheet from our NAT MAC catalog (composition, sizes and applications) and public references from the copper industry. Values are for reference and may vary by standard, temper and heat.
