Cast Copper Alloy Information
This page is dedicated to all things related to the Cast Copper Brasses that we produce.
Brasses
Originally Brass was an alloy of copper (Cu) and zinc (Zn), we learned how to manpulate their in proportions to obtain variations in colour as well as mechanical, electrical, acoustic, and chemical properties.
Brass was and is still used extensively for musical instruments such as the trumpet, cornet, flugelhorn, trombone, tuba, baritone horn, alto (tenor) horn and French horn, and that's why we have our "Brass Bands", and a key grouping of instruments, part of the the wind section, in any orchestra. Brass is still commonly used in applications where corrosion resistance and low friction are experienced, such as locks, hinges, ammunition casings, zippers, hose couplings, electrical plugs and sockets, and often in replica jewelry. and is often used in situations in which it is important that sparks not be struck, such as in fittings and tools used near flammable or explosive materials. Brasses are known for their antimicrobial and anti-biofouling properties as well.
Brass is not suitable for marine, and certain inland water use, because of a process discovered centuries after Brass' initial take-up, call de-zincification. The British Navy claimed, that "dezincification had more effect than the German navy in putting HM ships out of action in the First World War".
De-zincification
Dezincification is an example of dealloying, in which one of the constituents of an alloy is preferentially removed by corrosion. The dezincification of brass is a little more complicated than the similar graphitisation of cast iron since the zinc and copper are not present as separate constituents but as alpha and beta solid solutions. Instead of the zinc being selectively leached out from the brass, the zinc and copper both pass into solution together, but the copper is then almost immediately redeposited in virtually the same position that it occupied originally. The result therefore is to remove the zinc as a product of corrossion and leave a residue of copper. Dezincified brass, like graphitised cast iron, retains the original shape and dimensions of the metal component before corrosion but, in both cases, the residue is porous and has very little strength
Alloying Agents - Sub Divisions of Brass
So the original Brass alloy of Copper (Cu) and Zinc (Zn), was found to be inadequate and not fit for purpose in certain of its uses, as the issue with de-zincification epitomised. Engineers and Metallurgists worked on addressing these various issues and the alloying of brass evolved.
Brasses are now broken down into sub-categories aligned to their alloying elements. These Brasses contain specified quantities of Lead (Pb), Tin (Sn), Manganese (Mn), Silicon (Si), Bismuth (Bi) and Selenium (Se). There are six subcategories of cast brasses:
- C83300-C83999: [Cu-Zn-Sn-Pb(75-89%Cu)] Copper-Tin-Zinc and Copper-Tin-Zinc-Lead Alloys (Red Brass, also called Gunmetal, and Leaded Red Brasses)
- C84000-C84999: [Cu-Zn-Sn-Pb(75-89%Cu)] Copper-Tin-Zinc and Copper-Tin-Zinc-Lead Alloys Semi-Red Brass and Leaded Semi-Red Brasses
- C85000-C85999: [Cu-Zn-Sn-Pb(57-74%Cu)] Copper-Zinc Alloys (Yellow Brasses)
- C86000-C86999: [Cu-Zn-Mn-Fe-Pb] Manganese Bronze and Leaded Manganese Bronze (High Strength Yellow Brasses)
- C87000-C87999: [Cu-Zn-Si] Copper-Silicon Alloys (Silicon Bronzes and Silicon Brasses)
- C88000-C89999: [Cu-Bi]Copper-Bismuth and Copper-Bismuth-Selenium [Cu-Bi-Se] Alloys
In the sections that follow (which you expand or collapse by clicking), we provide a full listing of the alloys available, we provide the UNS designations and the common equivalents in other designations.
These Brasses have either element combinations of Copper, Tin & Zinc or Copper, Tin, Zinc & Lead. [Cu-Zn-Sn-Pb(90-96%Cu)]
They typically have a golden-yellowish hue but more often closer to red if there is a higher percentge of copper present. Hence, the etymology of “Red Brass”, which is how it is often times referred to as, especially in the United States, whereas it is also called "Gun Metal" on the other side of the Atlantic, and in the former European Colonies. This dates back to the 16th century, when Brass was used in the manufacture of light cannons (since superseded by steel).
Good corrosion resistance, excellent castability and moderate strength. Lead content ensures pressure tightness. Alloy C83600 is one of the most important casl alloys, widely used for plumbing filtings, other waler-service goods. Alloy C838DD has slighlly lower strength, but is essentially similar in properties and application.
These Brasses have either elment combniations of Copper, Tin & Zinc or Copper, Tin, Zinc & Lead. [Cu-Zn-Sn-Pb(75-89%Cu)]
Semi Red Brass has higher Zinc content than Red Brass which reduces corrosion resistance, lowers input costs but does not impact strength. They still retain outstanding aquaeous corrosion resistance and hence are used in plumbing applications.
Yellow Brasses have element combinations of Copper, Zinc & Tin or Copper, Zinc, Tin & Lead. [Cu-Zn-Sn-Pb(57-74%Cu)]
These are relatively low in cost and have excellent castability, high machinabi lity and favorable finishing characteristics. Their corrosion resistance, while reasonably good, is lower than that of the red and semi-red brasses
High Strength Yellow Brasses have element combinations of Copper, Zinc, Manganese, Iron & Lead. [Cu-Zn-Mn-Fe-Pb]
Manganese bronze alloys can operate under very high loads and speeds. Besides excellent mechanical qualities, these alloys have good corrosion resistance. The combination of copper, manganese, aluminum, and iron result in excellent tensile strength. The Iron is used to increase strength inexpensively, whilst Manganese is used to improve strength without a proportional reduction in ductility. These alloys have high mechanical strength, good corrosion resistance and favorable castability. They can be machined, but with the exception of C86400 and C86700, are less readily machined than leaded compositions. Alloy C86300 can altain tensile strengths exceeding 790 MPa (115 ksi).
Manganese Bronze is used for a wide range of mechanical components and devices, such as gears, levers, brackets, valve and pumps for both fresh and seawater service. When used for high strength bearings, alloys C86300 and C86400 require hardened shafts, preferrably at Rockwell C of 55-60.
These Brasses have either elment combniations of Copper, Tin & Zinc. [Cu-Zn-Si]
Moderate-to-high strength alloys with good corrosion resistance and favorable castjng properties. Used for mechanical products and pump components where combination of strength and corrosion resistance is important. Similar compositions are commonly die and/or permanent mold cast in Europe and the U.K.
These alloys have element combinations of either Copper-Bismuth [Cu-Bi] or Copper-Bismuth-Selenium. [Cu-Bi-Se]
Also referred to as, lead-free bronze, bismuth bronze, copper-bismuth bronze, lead-free bismuth bronze, bismuth tin bronze, and lead-free bismuth tin bronze. The benefits of for example, C89835 include good machinability, plating and polishing characteristics, castability at lower temperatures, and superior microstructural characteristics. With a maximum lead content of 0.05%, the Bismuth alloying agent is utilized as a replacement for the lead, providing similar characteristics to a lead-based copper alloy.
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