June 2000

Copper-Nickel Alloys - Marine Supreme: Introduction

Copper Applications in Metallurgy of Copper & Copper Alloys

By Vin Callcut

Copper, the noblest of the metals in common use, has excellent resistance to corrosion in the atmosphere and in water. In seawater, the copper-nickel alloys have superior resistance to corrosion coupled with excellent anti-fouling properties needed to meet modern demands economically. This article presents an introduction to the alloys and provides references to many other articles, on line and in print, which contain more information on the alloys' properties and applications.

Copper cladding of wood-hulled warships was introduced in the 18th century to prevent damage by wood-boring insects and worms such as the teredo. It was also discovered that copper prevents biofouling by algae and mollusks. This antifouling property meant that ships could stay at sea for long periods without cleaning. Nelson's successful blockade tactics and subsequent victory at Trafalgar were partly due to the superior speed of his clean-hulled, copper-clad ships.

Many of the underwater wrecks now being explored are found to have their copper alloy fittings largely intact. Pulleys salvaged from the 16th Century Mary Rose would only need to be cleaned of deposits to be still usable (See Mary Rose, this issue of Innovations).

The addition of nickel to copper improves its strength and durability as well as its resistance to corrosion, erosion and cavitation in all natural waters, including seawater and brackish, treated or polluted waters. Copper-nickel alloys also show excellent resistance to stress-corrosion cracking and corrosion fatigue. The added advantage of resistance to bio-fouling make it an ideal material for application in marine and chemical environments such as ship and boat hulls, desalination plants, heat exchange equipment, seawater and hydraulic pipelines, oil rigs and platforms, fish-farming cages and seawater intake screens.

This article discusses typical applications for copper-nickel alloys and presents the reasons for their selection. The two main alloys in this family contain respectively 10% or 30% nickel, as well as small amounts of iron and manganese. Table 1 lists typical international and national standards to which the materials may be ordered in wrought and cast forms. Table 2 lists commonly standardized compositions.

Table 1. Applicable Standards for various Wrought and Cast Products
StandardsApplicable Standard Numbers
B122 B111
EN† 1652 1652 1652 12451 12163 12166 12420 1982
ISO 429 1634 1634 1634 1635
1638 1640
† A new standard for materials for marine use is being prepared.
Note: This summary covers American (ASTM), European (EN replaces all previous national standards) and International Standards (ISO). It does not cover military standards.
Table 2.Standard Compositions of Wrought Copper-Nickel Alloys, North American and European Designations
American DesignationsComposition, % (Range or Max)
UNS Alloy No.CuPbFeZnNi (incl Co)SnMnOthers*
C70600 Rem 0.05 1.0-1.8 1.0 9.0-11.0 1.0
C71500 Rem 0.05 0.4-1.0 1.0 29.0-33.0 1.0
C71640 Rem 0.01 1.7-2.3 29.0-32.0 1.5-2.5 0.03S
*Special limits apply when the product is to be welded.
European DesignationComposition, % (Range or Max)
CuNi10-Fe1Mn CW352H Rem 0.05 0.1 1.0-2.0 0.5-1.0 9.0-10.0 0.02 0.02 0.05 0.03 0.05 0.2
CW353H Rem 0.05 0.1 1.5-2.5 1.5-2.5 29.0-32.0 0.02 0.02 0.05 0.05 0.5 0.2
CuNi30-Mn1Fe CW354H Rem 0.05 0.1 0.4-1.0 0.5-1.5 30.0-32.0 0.02 0.02 0.05 0.05 0.5 0.2
*Co max 0.1% is counted as Ni.

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