C715 Cupro-Nickel is a 70/30 copper nickel alloy that is almost entirely resistant to stress corrosion.  The addition of small amounts of iron and manganese make 70-30 CuNi ideal for use in applications involving high-velocity polluted seawater. Typical 715 CuNi applications for use in the chemical and desalination industries include tubes and tubesheets for condensers, evaporators and heat exchangers; tubes for carrying seawater; valve bodies; pump bodies and impellers. C71500 70-30 Copper-Nickel is known for its strength, workability, formability and weldability.

Marmetal stocks 715 70/30 Copper Nickel in Sheet, Plate, Bar, Pipe and Condenser Tube form, as well as Flanges, Fittings, Forgings and Castings.

Specifications for C715 70/30 Copper-Nickel

ASTM ASME Military
Bar ASTM B151 ASME SB-151 MIL-C-15726
Forging MIL-C-24679
Sheet ASTM B171 ASME SB-171 MIL-C-15726
Plate ASTM B171 ASME SB-171 MIL-C-15726
Pipe ASTM B466 ASME SB-466 MIL-T-16420
Tube ASTM B111 ASME SB-111 MIL-T-15005
Mechanical Properties for for C715 70/30 Copper-Nickel 

BAR – Round, Hex and Square
Commercial
TEMPER SIZE TENSILE, KSI, MIN YIELD@0.5%, KSI, MIN Elong. % Min
O60 up to 1/2″ 52 18 30
over 1/2″ to 1″ 48 18 30
over 1″ 45 18 30
H01 up to 1/2″ 65 50 10
over 1/2″ to 1″ 60 45 15
over 1″ to 3″ 55 35 20
over 3″ to 5″ 45 18 20
MIL-C-15726
TEMPER SIZE TENSILE, KSI, MIN YIELD@0.5%, KSI, MIN Elong. % Min
O60 All Sizes 45 18 30
H01 up to 1/2″ 65 50 10
over 1/2″ to 1″ 60 45 15
over 1″ to 3″ 55 35 20
SHEET/PLATE
Commercial
TEMPER SIZE TENSILE, KSI, MIN YIELD@0.5%, KSI, MIN Elong. % Min
M20 / O25 up to 2-1/2″ 50 20 30
over 2-1/2″ 45 18 30
MIL-C-15726
TEMPER SIZE TENSILE, KSI, MIN YIELD@0.5%, KSI, MIN Elong. % Min
O60 up to 3/16″ 50 20 30
M20 Soft over 3/16″ to 2-1/2″ 50 20 30
M20 Soft over 2-1/2″ 45 18 35
H01 up to 3/16″ x 24″ wide 60 30 10
H01 up to 3/16″ x over 24″ wide 55 25 10
M20 Hard up to 1/2″ x over 24″ wide 50 22 15
M20 Hard over 1/2″ x all widths 45 18 20
PIPE
Commercial
TEMPER SIZE TENSILE, KSI, MIN YIELD@0.5%, KSI, MIN Elong. % Min
O60 All Sizes 52 18 N/A
H80 All Sizes 70 45 N/A
MIL-T-16420
TEMPER SIZE TENSILE, KSI, MIN YIELD@0.5%, KSI, MIN Elong. % Min
O60 up to 4-1/2″ 50 18 30
over 4-1/2″ 50 16 30
TUBE
Commercial
TEMPER SIZE TENSILE, KSI, MIN YIELD@0.5%, KSI, MIN Elong. % Min
O61 All Sizes 52 18 N/A
MIL-T-15005
TEMPER SIZE TENSILE, KSI, MIN YIELD@0.5%, KSI, MIN Elong. % Min
O61 All Sizes 52 18 N/A
Compositions for C715 70/30 Copper-Nickel

COMMERCIAL

UNS No. Copper + Silver Nickel + Cobalt Manganese Lead Iron Zinc Phosphorus Sulfur Carbon
C71500 remainder 29.0-33.0 1.0 max 0.05a max 0.40-1.0 1.0a
C71520 65.0 min 29.0-33.0 1.0 max 0.02 0.40-1.0 0.5 0.02 max 0.02 max 0.05 max

aFor subsequent welding application, max levels are: Zinc 0.50, Lead 0.02, Phosphorus 0.02, Sulfur 0.02, Carbon 0.05

MIL-C-15726

UNS No. Copper Nickel + Cobalt Manganese Lead Iron Zinc Phosphorus Sulfur Carbon Cu + plus elements with specific limits, min
C71500 65.0 min 29.0-33.0 1.0 max 0.02 max 0.40-1.0 0.50 max 0.02 max 0.02 max 0.05 max 99.5

MIL-T-16420

UNS No. Copper + Silver Nickel + Cobalt Manganese Lead Iron Zinc Phosphorus Sulfur Carbon Cu + plus elements with specific limits, min
C71500 65.0 min 29.0-33.0 1.0 max 0.02 max 0.40-1.0 0.50 max 0.02 max 0.02 max 0.05 max 99.5

MIL-T-15005

UNS No. Copper + Silver Nickel + Cobalt Manganese Lead Iron Zinc Phosphorus Sulfur Carbon
C71500 remainder 29.0-33.0 1.0 max 0.02 max 0.40-1.0 0.50 max 0.02 max 0.02 max 0.05 max
Physical Properties for C715 70/30 Copper-Nickel

Density @ 68o F 0.323 lb/in3
Melting Range 2140-2265o F
Hot Formability Good
Cold Formability Good
Machinability rating (C360 = 100) 20
Brazing Excellent
Soldering Excellent
Gas-shielded arc welding Excellent
Oxy-acetylene welding Good
Carbon-arc welding Not recommended
Coated metal-arc welding Good
Resistant welding: spot and seam Good
Resistance Welding: butt Good
Applications for C715 70/30 Copper-Nickel

* Condensers
* Evaporators
* Tubesheets
* Valve Bodies
* Pump Bodies
* Impellers
* Fire Supression Systems
* Brake Lines
* Heat Exchangers
* Fasteners
* Fittings
* Flanges