CuCrZr (CW106C / C18150)
Age-hardened copper, for welding electrodes
Typical values for the temper in the title
CuCrZr is copper with about 1% chromium and a little zirconium, hardened by aging. It keeps high electrical and thermal conductivity (at least 75–80% IACS), but is much stronger and harder than pure copper, and keeps its hardness when hot.
This makes it the standard material for spot welding electrodes and caps (ISO 5182 Class A2/2, RWMA Class 2), seam welding wheels, electrode holders, and parts needing both conductivity and strength: contacts, heat spreaders and mold cooling inserts.
Mechanical and physical properties
| Property | Value | Note |
|---|---|---|
| Tensile strength Rm | ≥490 MPa (electrodes) | |
| Yield strength Rp0.2 | ≥430 MPa (electrodes) | |
| Elongation A | ≥15% | |
| Modulus of elasticity E | ≈120–130 GPa | |
| Density ρ | 8.9 g/cm³ | |
| Machinability | Moderate | relative rating in the site database |
Chemical composition (wt %)
| Element | Range | Role |
|---|---|---|
| Cr chromium | 0.5–1.2 | age strengthening |
| Zr zirconium | 0.03–0.3 | resistance to softening when hot |
| Fe iron | max 0.08 | |
| Si silicon | max 0.1 | |
| Cu copper | balance |
Ranges per EN (CW106C). In American C18150 chromium goes up to 1.5%. Electrode properties per Luvata.
Tempers and heat treatment
CuCrZr gains strength by solution treatment and aging, sometimes with cold work between the steps.
| Condition | Properties | When to choose it |
|---|---|---|
| Solution treated and aged | balanced strength and conductivity | most uses |
| Solution treated, cold worked and aged | maximum strength and hardness | electrodes |
Applications
- Spot welding electrodes and caps
- Seam welding wheels
- Electrode holders
- Loaded electrical contacts
- Mold cooling inserts
Fabrication
Machining
Moderate: copper "smears". Sharp tools with positive rake.
Welding
Do not fusion weld: heat cancels the aging and the material softens. Join mechanically or by soldering.
Choosing vs beryllium copper
CuCrZr is more conductive and cheaper, without beryllium dust risk. BeCu is stronger.
Compared with similar materials
| Material | Rm / Rp0.2 | Welding | When it is the better choice |
|---|---|---|---|
| C17200 (CuBe2) | 1380 / 1190 MPa | Electron beam / laser | beryllium copper: stronger, less conductive · material page |
| C110 (Cu-ETP) | 220–275 / 70–145 MPa | Good — Silicon Bronze | pure copper: more conductive, soft · material page |
| Copper-Tungsten (W-Cu) | 585–654 MPa (Class D) / | No — brazing | copper-tungsten: for electrodes at higher load and heat · material page |
Common mistakes
Welding a CuCrZr part
It softens in the weld zone.
Using pure copper for an electrode
It deforms and wears quickly.
Heating above the aging temperature for long
The material softens.
Equivalents, standards and supply
| DIN | 2.1293 |
|---|---|
| UNS | C18150 |
| ISO | 5182 A2/2 |
| RWMA | Class 2 |
| Standards | EN 12163 / EN 12165 / ISO 5182 |
| Forms | bar · disc · forging · electrodes |
| Producers | Wieland · Luvata · KME |
Learn more
Values are typical and for comparison only. For design, rely on the standard and the mill certificate. Sources: Copper Development Association (copper.org), ASTM B111 and B124, producer data sheets, and the METAL HUB materials database.
Updated: October 31, 2026