The Brasses 



29 



physical and general mechanical properties are given in 

 Table 4 on page 48 for the common forms (strip, rod, and 

 tube). Charts 59 to 77 on pages 49 to 53 show in greater 

 detail the influence of ccld working and anneahng on the 

 mechanical properties of this alloy. 



Spring brass containing 75 per cent of copper has 

 excellent cold-working properties and can be readily 

 fabricated by spinning, drawing, forging, and upsetting. 

 It is not generally hot-worked as its hot plastic range is 

 extremely narrow. Spring brass is suitable for forming 

 into springs where loads are not excessive and where 

 corrosion resistance is important. It is commonly fabri- 

 cated into sheet and strip. Its physical and general 

 mechanical properties are given in Table 5 on page 54. 

 Charts 78 to 91 on pages 54 to 57 show more detailed 

 information. 



70-30, or cartridge, brass, deep-drawing, 2 and 1, and 

 common high brass are known generally as the high 

 brasses. These alloys possess the optimum combina- 

 tions of strength and ductility. They all have excellent 

 cold-working properties and can be readily spun, drawn, 

 forged, and upset. As a general rule they are not fabri- 

 cated by hot-working processes as the range in which 

 they are hot plastic is very narrow. 



Since the operations in which these alloys are used 

 require excellent ductility, those elements which have an 

 adverse influence on this property are very carefully 

 controlled. Iron because of its hardening action and 

 lead because of its influence on fire cracking are usually 

 limited to 0.05 per cent, maximum. Such impurities as 

 phosphorus, antimony, bismuth, nickel, chromium, and 

 aluminum are kept to a trace or less. 



Since alloys in this copper range are susceptible to 

 "season cracking," it is common practice to relief -anneal, 

 at low temperatures, formed parts that are to be used 

 under conditions of mild corrosion. 



High brasses are used for the manufacture of pins, 

 rivets, eyelets, snap fasteners, automobile radiator cores, 

 heating units, musical instruments, automobile lamp 

 bodies and reflectors, cartridge cases and clips, electrical 

 sockets, lamp bases, and many other drawn or formed 

 shapes. The high brasses are available in sheet and 

 strip, rod, wire, bar, and tube. Their physical and 

 general mechanical properties for the common forms 

 (strip and rod) are shown in Tables 6 to 9 on pages 58 to 

 76. Detailed data are given in Charts 92 to 158 on 

 pages 59 to 78. 



ALPHA-BETA BRASSES 



Hot Working. — The alpha-beta brasses, i.e., those con- 

 taining from 64 to 55 per cent copper, are much easier to 

 hot-work than the alpha; the ease of hot working increas- 

 ing as the copper content decreases. Although lead is 

 virtually insoluble in the alpha brasses and as such inter- 

 feres with hot rolling, there is reason to believe that the 

 beta phase will hold up to 1 per cent of lead in solution 

 as it is possible to hot-work by any process alpha-beta 



brasses containing this amount of lead. The alpha-beta 

 brasses are most commonly fabricated by hot processes 

 since they are most plastic under these conditions. 



Cold Working. — The alpha-beta brasses become in- 

 creasingly difficult to cold-work as the copper content 

 decreases. Those alloys containing less than about 

 58 per cent of copper are considered commercially 

 unsuited for any cold-working operations. The poor 

 cold-working properties of the alpha-beta brasses are 

 caused by the presence of the beta phase. The brasses 

 containing between 60 and 62 per cent of copper are suit- 

 able for parts requiring light cold-working properties. 

 Cold-working properties improve progressively as the 

 copper content increases to 64 per cent, at which point 

 the beta phase disappears and the characteristic proper- 

 ties of the alpha range are encountered. 



Annealing. — ^Like the alpha brasses, the alpha-beta 

 brasses can be rendered soft after cold-working opera- 

 tions by annealing within the temperature range of 

 700 to 1400°F. depending upon the properties required. 

 The alpha-beta brasses, however, can be hardened 

 slightly by quenching from the annealing temperature. 

 The hardening is produced by the formation of a greater 

 amount of beta in the alloy than would be produced by 

 air or furnace cooling. 



Physical Properties — General. — The alpha-beta 

 brasses possess the highest tensile properties and the 

 lowest ductility of any of the copper-zinc alloys. Both 

 of these properties are affected by the ratio of the beta 

 phase to the alpha phase. Alloys of the lowest copper 

 content, because of the greater percentage of beta phase, 

 are the strongest and least ductile. The alpha-beta 

 brasses with the higher copper content approach the 

 alpha brasses containing 64 per cent of copper in ductility 

 and strength. 



At the appearance of the beta phase an increase in 

 electrical and thermal properties over those of the low- 

 copper alpha brasses is effected. Muntz metal contain- 

 ing 60 per cent of copper, the most important of the 

 alpha-beta brasses, has an electrical conductivity slightly 

 higher than that of 70-30 brass. 



Muntz metal, known also as "yellow metal," has 

 extremely good hot-working properties, being hot plastic 

 over a wide temperature range. It possesses the highest 

 tensile strength and lowest ductility of the brasses and 

 consequently only fight cold-working operations are 

 possible with it. 



Muntz metal is widely used in architectural work for 

 panel sheets, grilles, door stiles, and so forth. It is also 

 used for tube sheets and baffie and support plates in heat 

 exchangers. It also has been used for condenser tubes 

 and as pipe for domestic and industrial plumbing. It 

 is fabricated in sheet and strip, plate, rod, bar, and tube. 

 Its physical and general mechanical properties are given 

 in Table 10 on page 79. Charts 159 to 186 on pages 

 80 to 86 show the range of properties that can be 

 secured. 



