Brass products

Brass is an alloy that consists of copper and zinc. Different types of brass are used in the industry. The zinc content of brass plates used in ordinary toys is 30-40%, which is the same type of alloy as used for brass wires. Cast brass generally contains 35-45% of zinc; the higher the zinc content, the more the alloy contracts, and the more porous it is. Traditionally, brass is cast in large vats. Copper and zinc is put in various layers into the preheated vat, and sometimes even scrap brass is added to these two metals. Finally the inlay is covered in carbon dust so as to stop the zinc from evaporating, and the vat is placed into the oven. During the melting process, a part of zinc (5-8%) is burnt even if all the necessary precautions are taken, so this has to be taken into account when producing an alloy with a specific composition. The rigidity of brass can be significantly different, depending on the ration of its components, it can be fluid, buffable, resistant to atmospheric effects. If exposed to moist air containing carbon-monoxide, brass will develop a bright green basic cupric carbonate layer. It is significantly less resistant to corrosion than copper. A brass alloy with a zinc content of 5-15% is called tombac, and it is used for manufacturing ormolu. A brass alloy with a zinc content of 15-25% is suitable for manufacturing brass wires and brass plates. A brass alloy with a zinc content of 25-35% is very sturdy, it is suitable for manufacturing machine parts. In older times it was also used to cast cannon barrels, therefore it is also known as “gunmetal”.   

Brass can be better drawn when cold, if the zinc content is 15-20%. This alloy cannot be drawn when hot. If the zinc content is 35-40%, then the allow can be drawn both hot and cold. With a higher zinc content, the ductility decreases significantly, but at a zinc content of 70-90%, the metal becomes ductile again, but only when glowing hot. Brass is most rigid when the zinc content is 28,5%.

Application of brass

• radiator tubes, gas and water fittings, valves, machine parts, gears

• welding materials (CuZn4oSi)

• furniture industry

• bathroom fittings,

• home equipment,

• construction industry

• condensers, industrial heat exchangers made of special alloy brass tubes (e.g. CuZn20Al2)

Source:

• Pattantyús Gépész- és Villamosmérnökök Kézikönyve 1. kötet. (Manual for mechanical and electrical engineers, Vol. 1)  Műszaki Könyvkiadó, Budapest, 1961.

• József Bokor (ed.). Sárgaréz, A Pallas nagy lexikona. (Brass)

• Györgyné Gruber. Szabványos színesfémek és ötvözeteik jellemzői és alkalmazása. (Characteristics and application of standard non-ferrous metals and their alloys)