Copper-Nickel-Silicon
UNS C18000 · CuNi2Si, CuNi3Si, CuNi7Si2Cr1
Copper-nickel-silicon alloys keep their strength and their conductivity when the part runs hot, in moulds, welding tools, engines and contacts.
Alloy family
What this family is good at
Formed soft, hardened by heat treatment
These alloys are shaped in their soft state, then hardened by heat treatment. They retain high strength while maintaining a significant portion of copper's thermal and electrical conductivity, up to 45% IACS for NS6 in our catalogue. They contain no beryllium or lead.
Parts that run hot
The family retains its strength at high temperatures and resists stress relaxation, which is the slow loss of clamping or spring force under heat. NS30 keeps its properties up to 350 °C and dissipates heat quickly, which shortens cycle times in moulding. This is why it goes into mould inserts and hot runner manifolds, welding shanks and wheels, and plunger tips for high-pressure die casting.
Friction parts in engines and machines
NS30 combines wear and galling resistance with good impact and fatigue behaviour, and it is non-sparking with a low magnetic permeability. It is machined into valve seats, guides and liners, bearings and bushings, and other valve train parts. NS5 and NS6 serve the same parts in bars, with more conductivity and less strength.
In the TER temper, NS30 bars are guaranteed at a minimum tensile strength of 900 MPa, with a hardness of 270 HB.
Strip for contacts, switches and relays
Siclanic® S is the family's strip grade, CuNi2Si compliant with CW111C. It is stamped, bent, soldered or welded in the soft state, then heat treated for strength and fatigue resistance. It serves contact blades, switches, circuit breakers, thermostats, contactors and relay parts, as well as automotive commutators and railway parts.
The grades and their standards
NS6, CuNi3Si (UNS C18000), and NS5, CuNi2Si, CuNi3Si, come in bars compliant with RWMA Class 3. NS5 is also compliant with CW111C, 2.0855, DTD 498 and NFL 14701. NS30, CuNi7Si2Cr1, is the strongest grade of the family, supplied in bars.
Strength from heat treatment, with electrical conductivity up to 45% IACS for NS6, and no beryllium or lead.
Stable at high temperature and resistant to stress relaxation; NS30 keeps its properties up to 350 °C.
Siclanic® S strip is stamped, bent, soldered or welded in the soft state, then hardened by heat treatment.
Range at a glance
The extent of this family's measured properties across its active variants — a range, never a single figure.
140 – 800 MPa
36/54 measured
270 – 900 MPa
37/54 measured
3 – 30 %
33/54 measured
160 – 270 HB
18/54 measured
24 – 45 %IACS
24/54 measured
8.7 – 8.9 g/cm³
30/54 measured
84 – 180 W/m·K
30/54 measured
All Copper-Nickel-Silicon references
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Family highlights
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Used in
- automotive
- Electronics & Connectors
- industry
- Energy & Nuclear
Specify it with an engineer
Choosing the grade that keeps both strength and conductivity
Tell us the operating temperature, the load and the current or heat the part must carry. Our engineers recommend the grade, the form and the heat-treatment state that fit.