Copper-Zinc Alloys Brasses

The principal alloying ingredient of the brasses is zinc. Other alloying ingredients include lead, tin, and aluminum. Machinability is improved by the addition of lead, which does not improve corrosion resistance. Strength and dealloying resistance is increased by the addition of approximately 1% tin. 

Compatibility of Copper, Aluminum Bronze, and Red Brass with Selected Corrodents 

Copper sulfate Cupric chloride, 5% Cupric chloride, 50% X X X X 

Magnesium chloride Malic acid Manganese chloride 300/149 X X 90/32 X 

The chemicals listed are in the pure state or in a saturated solution unless otherwise indicated. Compatibility is shown to the maximum allowable temperature for which data are available. Incompatibility is shown by an X. A blank space Indicates that data are unavailable. When compatible, corrosion rate is 20 mpy. 

Various names have become attached to brasses of different zinc content. Muntz metal, 40% Zn-Cu, is used primarily for condenser systems that use fresh water (e.g.. Great Lakes water) as coolant. Naval brass is a similar composition, but containing 1% Sn. Manganese bronze is also similar, containing about 1% 

Yellow brass, 30% Zn—Cu, is used for a variety of applications where easy machining and casting are desirable. The alloy gradually dezincifies in seawater and in soft fresh waters. This tendency is retarded by addition of 1% Sn, the corresponding alloy being called admiralty metal or admiralty brass. Addition of small amounts of arsenic, antimony, or phosphorus stUl further retards the rate of dezincification the resulting alloy, called inhibited admiralty metal, is used in seawater or fresh-water condensers. 

Red brass, 15% Zn-Cu, is relatively immune to dezincification, but is more susceptible to impingement attack than yellow brass. 

Dezincification, as one type of deaUoying, was defined in Section 2.4. Other types of dealloying include the selective dissolution of copper in copper-gold alloys. 

In brasses, dezincification takes place either in localized areas on the metal surface, called plug type (Fig. 20.4), or uniformly over the surface, called layer type (Fig. 20.5). Brass so corroded retains some strength, but has no ductility. Layer-type dezincification in a water pipe may lead to splitting open of the pipe under conditions of sudden pressure increase and, for plug type, a plug of dez-incified alloy may blow out, leaving a hole. Because dezincified areas are porous. 

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Dezincification is the selective corrosion of copper-zinc alloys (brass) with more than 15% zinc, in which porous copper deposits form on the corroded parts. Although less common, similar phenomena have also been observed in other copper alloys such as copper-aluminum (aluminum stripping), copper-tin (detinning), and copper-nickel (nickel stripping). 

Figure 20.3. Trends of dezincification, stress-corrosion cracking, and impingement attack with increasing zinc content in copper-zinc alloys (brasses).

Blow molding Alruninum, beryllium copper, zinc alloy, brass, stainless steel... 

Copper-zinc alloys (brass) are extensively used in heat exchangers. They are susceptible to SCC when in contact with ammonia or other amino-compounds such as urea. The phenomenon was first observed in the British colonies when brass cartridges were stored for prolonged times near horse stables. It has since also been known as season cracking. Stress corrosion cracks in brasses are most often, but not always, intergranular. 

Copper-zinc alloys (brasses) with more than 15 % zinc are susceptible to a type of dealloying CtiUed dezincification. Some aluminum bronze (Cu-Al) alloys, especially those containing more than 8 % aluminum, are also susceptible to dealloying. The dealloying in Cu-Al alloys can be prevented by adding more than 3.5 % nickel or by heat treating to obtain an a + P microstructure [79],... 

Heterogeneous systems (multiphase systems) Water together with ice at 0°C, oil-water emulsions, some copper-zinc alloys (brass), beer (with foam and bubbles). 

Copper nickels or cupronickels are alloys that result from addition of 3 to 30% Ni to copper. Nickel silvers are copper-zinc alloys (brasses) that contain some nickel. Copper nickels and nickel silvers have an alpha or fee structure and good mechanical strength and forming characteristics. Cupronickels are the most corrosion-resistant copper-based alloys. For example, the long-... 

Copper Copper Copper-zinc alloys ( brass )... 

Copper—Zinc Brasses. Copper—zinc alloys have been the most widely used copper alloy during the 1990s. It is no accident that the word brass is included in the name of many copper alloy manufacturers. The manufacture of brass buttons and other brass artifacts was the principal reason for the estabhshment of the U.S. copper alloy industry in Connecticut during the 1800s. 

Alloys containing only a few per cent of zinc may fail if the stresses are high and the environment sufficiently corrosive. Most types of brass, besides the plain copper/zinc alloys, appear to be susceptible to stress corrosion. An extensive investigation of the effect of additions to 70/30 brass was carried out by Wilson, Edmunds, Anderson and Peirce , who found that about 1% Si was markedly beneficial. Other additions were beneficial under some circumstances and none of the 36 additions tested accelerated stress-corrosion cracking. Further results are given in later papers ... 

One of several corrosion resistant copper/zinc alloys (e.g. 70% Cu + 30% Zn). See Admiralty brass. 

Copper-zinc alloys with a higher zinc content (brass) cannot be ground or formed into flake pigments on account of their brittleness. Controlled oxidation of natural bronze powders converts them into fired bronze powders. These shades (e.g., English green, lemon, ducat gold, fire red) are produced as a result of interference effects that depend on the thickness of the oxide coating. 

DEZINCIFICATION. A form of electrolytic corrosion observed in sume brasses where the copper-zinc alloy goes into solution with subsequent redepnsition of the copper. The small red copper plugs thus formed in the brass are usually porous and of low strength. In recent years, the term dcziticilicalion lias also been applied in a more general sense to signify any metallic corrosion process that dissolves one of the components from an alloy. 

Brass is a copper-zinc alloy. What is the mass in grams of a brass cylinder having a length of 1.62 in. and a diameter of 0.514 in. if the composition of the brass is 67.0% copper and 33.0% zinc by mass The density of copper is 8.92 g/cm3, and the density of zinc is 7.14 g/cm3. Assume that the density of the brass varies linearly with composition. 

Dezincification. Copper-Zinc alloys containing more than 15% zinc are susceptible to dezincification. In the dezincification of brass, selective removal of zinc leaves a relatively porous and weak layer of copper and copper oxide. Corrosion of a similar nature continues beneath the primary corrosion layer, resulting in gradual replacement of sound brass by weak, porous copper. Uniform dealloying in admiralty brass is shown in Figure 6.25.5,7,53,54... 

Brass is basically a copper- zinc alloy bronze is a copper- tin alloy. In practice both often contain many other metals. Their high machinability, resistance to corrosion, and ease of soft soldering make them very useful in apparatus construction. Owing to the volatility of zinc, brass should not be used in vacuum components that must be baked out or operated hot. Certain bronzes such as phosphor bronze are useful for springs and diaphragms beryllium copper is also useful in these applications. 

There are two types of solders soft and hard. Soft solders usually consist of a mixture of lead and tin and the heat required to melt them is supplied by a soldering iron. Hard solders include brass (copper-zinc alloys) solders, silver solders, copper solders, nickel-silver solders, and solders for light alloys the heat to melt them is usually supplied by a blow torch. 

The bronze samples were obtained in 30.5 cm x 30.5 cm sheets from the C.R. Hills Co. (Berkley, MI). The bronze alloy was cast as Alloy 220 with 90% copper and 10% zinc by weight, with trace lead and iron impurities. It was in sheet rolled form at 18 gauge (1.00 mm thickness) and with a density of 8.80 g/cm. Historically, bronze was classified as copper/tin alloy with a minimum 10% by weight tin, while brass was a copper/zinc alloy with at least 10% zinc. The contemporary classification of "bronze" has been expanded to encompass a much wider range of copper alloys with bronze-like structures, properties, and color, but which contain no tin. Thus, although it is commercially classified as bronze, the sample utilized in this work was historically brass. 

Alkylamines are corrosive to copper, copper-containiag alloys (brass), aluminum, zinc, zinc alloy, and galvanized surfaces. Aqueous solutions of alkylamines slowly etch glass as a consequence of the basic properties of the amines in water. Carbon or stainless steel vessels and piping have been used satisfactorily for handling alkylamines and, as noted above, some alkylamines can act as corrosion inhibitors in boiler appHcations. 

BRASS - A copper-zinc alloy containing up to 40% zinc and some smaller amounts of other metals. 

Alloying characteristics Brass (copper-zinc alloy), aluminum Building/construction, fittings, automotive rt... 

Brasses are the best known copper alloys. They are primarily binary copper-zinc alloys and they contain up to 40 % zinc. The best known brass (yellow or architectural brass) is the 70 % Cu -30 % Zn alloy. All brasses can be cast readily they are ductile and they can be worked into complex shapes. Brass seems so commonplace in everyday life that it is almost taken for granted. For instance in our houses, it is encountered as doorknobs, taps, valves and lighting fixtures it is even more frequently encountered in commercial buildings. 

The ferrous range covers low alloy, carbon and tool steels as well as corrosion and heat-resistant steels. The non-ferrous range covers aluminium and zinc alloys and the copper-based alloys, brasses, bronzes and gunmetal. 

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