CuNi2Si

2.0855

copperbronze_wrought

Nickel-silicon precipitation-hardened copper alloy combining high strength (UTS ~700 MPa aged) with good electrical conductivity (35–45% IACS) and excellent stress relaxation resistance at elevated temperatures. Lead-free and RoHS compliant — the modern replacement for CuBe2 in many connector applications where beryllium toxicity is a concern. Trade names: Wieland K55 (Wieland), C70250 (Olin Brass). Used for automotive high-current connectors, IC lead frames, relay springs, fuse clips and miniaturized electronic contacts.

International equivalents

Flag	Standard	Country	Grade	Number	Match
🇺🇸	UNS	USA	C70250	C70250	REF
🇪🇺	EN	Europe	CW109C	—	100%

Sources: ASTM B534, EN 12163

Chemical composition comparison (wt%)

Side-by-side: CuNi2Si (EN 12163) vs CW109C (EN) (EN 12163)

Element	CuNi2Si (EN 12163)	CW109C (EN)	Overlap
Si	—	0.4–0.8%	—
Ni	—	1.6–2.5%	—

Mechanical properties

Solution annealed

Property	Value	Unit
Tensile Strength	300–380	MPa

Precipitation hardened

Property	Value	Unit
Tensile Strength	620–720	MPa
Yield Strength Rp0.2	550–660	MPa
Elongation A	5–12	%

General

Property	Value	Unit
Density	8.81	g/cm³
Electrical Conductivity IACS	35–45	%
Thermal Conductivity	170–200	W/mK

Compatibility verdict

CuNi2Si and CW109C: 100% composition match

Related materials

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