Iron has a favorable influence on the strength properties of copper-nickel alloys. Figure 13 Shows an example of an alloy with 10% Ni content. Improvements in the strength properties of CuNi30Mn1Fe be achieved by increasing both the iron and manganese contents by 2%. For example, strips and sheets made of alloy CuNi30Fe2Mn2 have a tensile strength of 440 n/mm2 and a 0.2% yield strength of 145 n/mm2.
Further increases in strength values can result with additives, such as aluminum or chrome. These values are shown in Tab. 12.
As is the case with all metallic materials, the material's strength is increased with repeated cold working. Copper-nickel alloys are no exception. With increased cold working, the tensile strength improves by 0.2% yield strength and hardness, while, on the other hand, the elongation at break values decrease (Figure 14).
There are three curable copper-nickel wrought alloys particularily worth mentioning, those with additions of aluminum, chromium or beryllium. The alloy with about 2% Al can be found in a cast or cured state. With the addition of beryllium, the largest increase in strength is achieved after undergoing curing. Such an alloy is already in use in the United States in marine technology .
High strenth, curable copper-nickel alloys with zinc content up to 6% , which usually contain other additives such as lead and zinc, are standardized in ASTMN 584.