CHAPTER VII 

 THE CUPRO -NICKELS 



The copper-base alloys of nickel, i.e., those in which 

 copper is the predominant alloj^ constituent, are commer- 

 cially available in two types: one containing 80 per cent 

 of copper and 20 per cent of nickel, and the other contain- 

 ing 70 per cent of copper and 30 per cent of nickel. Both 

 of these alloys are single-phase solid solutions of copper 

 and nickel and are known as the "cupro-nickels." 



Although these alloys have been known for many 

 years, they did not assume commercial importance 

 until about 1925. At that time the demand for con- 

 denser tubes capable of resisting the erosive-corrosive 

 attack of high-velocity salt water used as the coolant 

 in Navy surface condensers led to their commercial 

 development. 



Since that time 70-30 cupro-nickel has shown a marked 

 superiority as a condenser-tube alloy to the 80-20 alloy. 



The 80-20 cupro-nickel tube continues to find some use 

 as a condenser-tube material in less severe applications. 



Both of these alloys, in addition to their excellent 

 corrosion-resisting properties, possess tensile properties 

 similar to those of 70-30 brass and, in addition, are the 

 most resistant of the copper-base alloys to failure by 

 stress corrosion and corrosion fatigue. Both cupro- 

 nickels have been used in strip form for the manufacture 

 of ammunition component parts. Bolts, nuts, screws, 

 and similar parts are manufactured by cold-heading 

 operations. Because of their generally valuable proper- 

 ties, it is probable that their use will be extended. 



The physical and general mechanical properties of the 

 two cupro-nickels are given in Tables 1 and 2 on pages 

 227 and 234. More detailed data are given in Charts 

 1 to 39 on pages 228 to 238. 



Footnotes to Table 1 



' Refers to rod cold-drawn 50%; rod under 1 in. in diameter, ready-to-finish grain size, 0.( 



i Refers to a 1400°F. anneal (1 hr.). 



= Material cold-forged from soft rod (5—40% reduction of area). 



' Material cold-forged from cold-worked condition (40 %). 



<= Extruded, reduced, and drawn to ?4 by 0.049 in. 



^ Footnote e after 1300°F. anneal (1 hr.). 



' All tests conducted on 0.040-in. stock. 



^ 6 B. & S. Nos., hard, 0.070-0.015 mm. grain size at ready-to-finish, respectively 



' Material described in footnote h after 1300°F. anneal (1 hr.). 



