Copper and Copper-base Alloys 



of copper which are oxygen-free or have been deoxidized 

 by phosphorus or other deoxidants are not materially 

 affected by exposure to reducing atmospheres at elevated 

 temperatures. 



The presence of small amounts of phosphorus, silver, 

 arsenic, or antimony has the affect of raising the mini- 

 mum temperature at which copper will soften. In many 

 applications this higher annealing point is desirable 

 and silver in amounts up to 25 ounces per ton is fre- 

 quently specified. 



Fig. 1 — fetiuctuie of cold worked and annealed copper (tough pitch). 

 Etchant NH4OH + H202. Magnification 75 X. 



Corrosion Resistance. — Although the commonly avail- 

 able commercial coppers differ in their content of certain 

 minor constituents, none of these significantly alter 

 the characteristics of the metal in respect to its ability 

 to resist corrosion. 



Copper withstands atmospheric corrosion and sea- 

 water corrosion as satisfactorily as any other com- 

 mercially available metal, and it has been used for 

 centuries in construction where resistance to attack 

 of this nature is desired. In addition, copper is sub- 

 stantially immune to the chemical attack of a large 

 number and variety of industrial chemicals, although 

 copper ordinarily should not be used in contact with 

 oxidizing acids and most oxidizing agents, or in services 

 where alternate exposure to oxidizing conditions and 

 acid reagents is anticipated. 



Metallic salts readily susceptible of chemical reduction 

 are particularly dangerous in respect to the corrosion of 

 copper; and ferric, stannic, mercuric, and cupric com- 

 pounds, particularly, constitute a source of danger when 

 present in an otherwise non-oxidizing acid solution, 

 which of and by itself might be inactive with respect to 

 copper. 



Ammonia and carbon dioxide in the presence of 

 moisture and in relatively low concentration can con- 

 stitute active corrosive agents with respect to copper. 



USES 

 Electrolytic (Tough-pitch) Copper. — Electrolytic (tough- 

 pitch) copper is the most important type of copper 

 commercially available. It is consumed in large quanti- 



ties by the electrical industry as wire for electrical 

 conductors, bars for bus-bar and commutator use, and 

 in forms such as sheet, strip, plate, etc., for widespread 

 architectural and industrial applications. 



Phosphor Deoxidized Copper. — The phosphor deoxi- 

 dized coppers are used for refrigerator tubing and 

 other applications where flaring, flanging, and spinning 

 operations might be deleteriously affected by the 

 presence of the copper-copper oxide eutectic dispersion 

 that is characteristic of electrolj^tic copper. The 



Fig. 2. — Embrittled copper (tough-pitch copper that has been 

 annealed in a reducing atmosphere). Etchant NHiOH + HzOi. 

 Magnification 75 X. 



phosphor deoxidized coppers also are preferable to 

 electrolytic copper when welding operations are to be 

 performed. The small residual quantities of phosphorus 

 reduce the electrical conductivity of copper materially, 

 as indicated in Chart 1, and phosphor deoxidized copper, 

 therefore, is seldom found in electrical applications. 



Oxygen-free Copper Containing No Residual Deoxi- 

 dant. — The modification in physical properties intro- 

 duced by the elimination of oxygen is indicated in the 

 data following. Although this type of copper is more 

 expensive to produce than the tough pitch, its satis- 

 factory performance in many manufacturing operations 

 and the reduction of manufacturing scrap consequential 

 to its use in such operations compensate in many 

 applications for its higher initial cost. 



Silver-bearing Coppers. — Silver present in amounts 

 ordinarily ranging from 5 to 6 ounces per ton up to 12 

 or 13, but in special cases running as high as 30 ounces 

 per ton, does not impair the electrical conductivity of 

 copper where this property is of significance and does 

 have the effect of increasing the equicohesive or recrystal- 

 lization temperature of the metal materially, as is 

 indicated by the data in Chart. 2. 



Copper with a silver content of from 8 ounces per ton 

 up has a recrystallization or softening temperature 

 materially in excess of the melting point of commercial 

 soft solders so that copper of this type can be soldered 

 into assemblies, such as automobile radiators, without 

 impairment of the physical properties imparted to such 

 copper by means of cold work. 



