Metal Alloys - Properties and Applications of Brass and Brass Alloys

Brasses are copper zinc alloys with a wide range of engineering uses. The addition of zinc to copper raises the strength and gives a range of properties, and the brasses are a very versatile range of materials. They are used for their strength, corrosion resistance, appearance and colour, and ease of working and joining. The single phase alpha brasses, containing up to about 37% zinc, are very ductile and easy to cold work, weld and braze. The dual phase alpha-beta brasses are usually hot worked.

There are many brasses, with properties tailored for specific applications by the level of addition of zinc. Minor amounts of other alloying elements may also be added.

Corrosion Resistance of Brass

Brasses are resistant to corrosion in many media. Please consult Austral Wright Metals for detailed advice on your application. Brasses are particularly susceptible to corrosion by solutions containing ammonia or amines. Alloys with more than about 15% of zinc may suffer dezincification, which leaves a weak, porous corrosion deposit of copper. Resistance to dezincification is greatly reduced by the addition of a small amount of arsenic to the alloy. Stress corrosion cracking, particularly by ammonia and amines, is also a problem with the brasses. Alloys containing more than about 15% zinc are most susceptible. Use of the annealed temper, and annealing or stress relieving after forming, reduces susceptibility to stress corrosion cracking.

Phase Diagram and Mechanical Properties of the Brasses

The phase diagram and the mechanical properties of the different types of brasses are demonstrated in the following image.

Composition of Different Types of Brass Alloys

The composition of different types of brass alloys are outlined in the following table:

Colouring of Brass Alloys

The brasses are often used for their appearance. As the zinc content is increased, the colour changes.

Gilding Metal Copper Alloy - Properties and Applications

Also known as red brass, commercial bronze, gilding metal. C22000 combines a rich golden colour with the best combination of strength, ductility and corrosion resistance of the plain copper-zinc alloys. It weathers to a rich bronze colour, and can be supplied in pre-patinated colours ranging from deep brown to green. It has a lower rate of work hardening than the copper-zinc alloys with higher zinc content, such as 260 and 272. This is an advantage in multistage pressing applications without interstage annealing. It has excellent deep drawing characteristics and resistance to pitting corrosion and stress corrosion cracking when exposed to severe weather and water environments.

Typical applications include: Architectural fascias, grillwork, jewellery, ornamental trim, vitreous enamel base, badges, door handles, escutcheons, marine hardware, munitions, primer caps, rotating bands, metallic bellows, pen, pencil and lipstick tubes etc.

Available forms of gilding metal: Austral Wright Metals can supply this alloy as sheet, strip and round bar.

Corrosion Resistance of Gilding Metal Copper Alloy

As an alpha brass with low zinc content, C22000 has excellent corrosion in most media. It is less susceptible to stress corrosion cracking than the higher zinc brasses such as 70/30 brass C26000, and is not considered susceptible in marine atmospheres. However, it should not be used in contact with aqueous ammonia and amines. C22000 should not be used with acetic acid, acetylene, brines, calcium chloride, moist chlorine, chromic acid, hydrochloric acid, mercury or its compounds, nitric acid and sodium hypochlorite.

Brass and Arsenical Brass Alloy - Properties and Applications

Also known as cartridge brass, spinning brass, spring brass. C26000, 70/30 Brass and C26130, Arsenical brass, have excellent ductility and strength, and are the most widely used brasses. Arsenical brass contains a small addition of arsenic, which greatly improves corrosion resistance in waters, but is otherwise effectively identical. These alloys have the distinctive bright yellow colour normally associated with brass. They have the optimum combination of strength and ductility in the copper-zinc alloys, coupled with good corrosion resistance.

C26000 is used for architecture, drawn and spun containers and shapes, electrical terminals and connectors, door handles, plumbers hardware. C26130 is used for tube and fittings in contact with water, including potable water.

Typical applications include: Architecture, grillwork, appliances, drawn & spun containers and components, radiator cores and tanks, electrical terminals, plugs and lamp fittings, locks, door handles, name plates, plumbers hardware, fasteners, cartridge cases, cylinder liners for pumps.

Available forms: Austral Wright Metals can supply this alloy as coil, sheet, plate, rods, bars, sections.

Corrosion Resistance of Brass and Arsenical Brass Alloy

C26000 has good corrosion resistance to weathering and very good resistance to many chemicals. It may undergo dezincification in stagnant or slowly moving salt solutions, brackish water or acidic solutions. Although it will resist most waters, C26130 is preferred as it contains a small arsenic addition which inhibits corrosion.

C26000 should not be used in contact with ammonia or ammonia compounds, as it may suffer stress corrosion cracking. Beware of corrosion inhibitors in piping systems containing carbon steels, which should be checked for compatibility with alloy C26000. 70/30 brass should not be used with acetic acid, acetylene, brines, calcium chloride, moist chlorine, chromic acid, hydrochloric acid, mercury or its compounds, nitric acid and sodium hypochlorite.

Yellow Brass Alloy

C26800, Yellow brass, is the single phase alpha brass with the lowest content of copper. It is used where its deep drawing properties and lower cost give an advantage. When welded, particles of beta phase may form, reducing ductility and corrosion resistance.

Engraving Brass 356 - Properties and Applications

Also known as extra high leaded brass. Engraving brass is traditionally used for machine engraved name plates due to its combination of high strength and free machining characteristics. It is an alpha / beta brass with a duplex structure which renders it unsuitable for acid etched work, for which the single phase brasses such as C26000 (70/30 brass) are preferable. C35600 weathers to the warm brown bronze tone which is desirable for name plates. C37000 is also available, with lower (0.9–1.4%) lead content. It has excellent free cutting properties, but machinability is only 70% of C35600.

Typical applications: engraved name plates and plaques, appliance trim, clock components, builders hardware, gear meters, free machining sheet and plate.

Available forms: Austral Wright Metals can supply this alloy as plate, sheet and bar.

Corrosion Resistance of Engraving Brass Alloy 356

C35600 has good corrosion resistance to weathering and fair resistance to many waters. There is some risk of failure by dezincification.

C35600 should not be used in contact with ammonia, ammonia compounds or amines, as it may suffer stress corrosion cracking. It is more susceptible to stress corrosion and dezincification than the single phase high copper brasses, but these are seldom a serious problem in atmospheric conditions.

Section Brass Alloy 380 - Properties and Applications

Section brass is a readily extrudable leaded alpha / beta brass alloy with a small aluminium addition, which gives a bright golden colour. The alloy is supplied only as extruded sections and shapes, with a minimum amount of cold work. The bright gold colour is lost if severe cold working operations are applied – alloy 385 is a better choice for cold work. The lead addition renders the alloy free cutting, and it is used widely in components produced by automatic machining. C38010 weathers to a warm bronze tone.

Typical applications: include builders hardware.

Available forms: Austral Wright Metals can supply alloy C38010 as extruded sections – rods, angles, channels, flats , other extruded shapes

Corrosion Resistance of Section Brass Alloy 380

C38010 has good corrosion resistance to weathering and fair resistance to many waters.

C38010 should not be used in contact with ammonia, ammonia compounds or amines, as it may suffer stress corrosion cracking.

Free Cutting Brass Alloy 385 - Properties and Applications

Free cutting brass ( also known as architectural bronze) is a significantly improved form of 60/40 brass, with excellent free cutting characteristics. It is used in the mass production of brass components on high speed lathes where maximum output and longest tool life are required, and where no further cold forming after machining is
needed.

The superior machining characteristics of alloy 385 are due to the rapid chill effect of continuous casting, which gives a fine uniform lead distribution without segregation, and suppresses the formation of brittle phases which cause tool wear.

The alloy gives:

• Superior surface finish without tooling modification
• Improved tool life and reduced tool sharpening
• Cleaner threads with no build-up and no breakage
• Cutting tools previously used with a negative rake can be modified to zero top rake

Typical applications: are nuts, bolts, screw threads.

Available forms: Austral Wright Metals are able to supply this alloy as extruded rods.

Corrosion Resistance of Free Cutting Brass Alloy 385

Alloy 385 has good corrosion resistance to weathering and fair resistance to many waters. Alloy 385 should not be used in contact with ammonia, ammonia compounds or amines, as it may suffer stress corrosion cracking.

This information has been sourced, reviewed and adapted from materials provided by Austral Wright Metals - Ferrous, Non-Ferrous and High Performance Alloys.

For more information on this source, please visit Austral Wright Metals - Ferrous, Non-Ferrous and High Performance Alloys.