176 



Copper and Copper-base Alloys 



ations, are necessary in order to obtain a surface suitable 

 for most welding. 



A summarization of mechanical properties and the 

 more important physical properties may be found in 

 Tables 2 and 3. Detailed mechanical properties of the 

 sUicon brasses may be found in Charts 4 to 27 on pages 

 178 to 185. 



ARSENICAL BRASS 



Within the past several years there has been developed 

 an alloy of copper and zinc in the alpha and beta range, 

 modified with 2 per cent of nickel, 1.25 per cent of iron, 

 and 0.60 per cent of arsenic. Lead is present to improve 

 machinability. This alloy is known as " arsenical brass " 



and finds wide application in the manufacture of valve 

 stems. It has excellent wear-resisting properties and, 

 by reason of its arsenic content, it is much more resistant 

 to failure by dezincification than arsenic-free alloys in 

 the same composition range. In addition, the presence 

 of the arsenic greatly improves the mechanical properties. 

 Arsenical brass has excellent hot-working properties 

 and can be cold-worked lightly. Owing to its lead con- 

 tent, its machinability is about 75 per cent that of free- 

 cutting brass. Its more important physical properties 

 and its general mechanical properties may be found in 

 Table 4 on page 186. Detailed data on the effect of 

 cold drawing and various annealing treatments are given 

 in Charts 28 to 39 on pages 186 to 189. 



TABLE 1 

 ALUMINUM BRASS 



General Data — Tubing 

 Copper, 75.78%; aluminum, 2.54%; arsenic, 0.04%; lead, 0.02%; zinc, balance 



Property 



Hard- 



Soft" 



Tensile strength, p.s.i. (000 omitted) 



Elongation, %in2in 



Apparent elastic limit, p.s.i. (000 omitted) 



Rockwell hardness F, He-in. ball, 60-kg. load 



Young's modulus of elasticity, p.s.i 



Melting point, °F 



Density, lb. per cu. in 



Electrical conductivity, <«" % I.A.C.S. at 68°F 



Thermal conductivity,"" B.t.u. per sq. ft. per ft. per hr. per °F., 68°F, 

 Specific gravity 



o Extruded, reduced, and cold-drawn to % by 0.049 in. 

 * Condenser tube anneal for 1 hr. (1050°F.). 



