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Copper Alloys Products

Bronze CASTING - BC

Bronze casting is excellent in terms of corrosion resistance, hydraulic resistance, seawater resistance and wear resistance, and thus is used for general machine components, ships, electricity and machine structural use.

Although bronze has been used since 3000 B.C., processing it to make products was generalized far later. The <Ilias> written by Homer describes how Hephaestus, the Greek god of fire, puts copper, tin, silver, gold, etc. into a furnace to make a shield for Achilles. 67~95% of artifacts from the Bronze Age were comprised of copper, and the proportion of copper and tin varied. In the Middle Ages they were used in a certain proportion to enhance efficacy. Alloys described in a Greek manuscript from the 11th century which is kept in a library in Venice reveals that copper and tin were mixed at the proportion of 8:1, which is very similar to the proportion used in bronze gun metal.

Bronze is not only harder but also easier to melt than copper, thus is easy to cast. It is harder than pure iron, and so is suitable for gun barrels or bearings for machines using the property of alloys. In history, iron was often used for tools and weapons instead of bronze not because of iron’s inherent merit, but because iron was more abundant than copper and tin. Bell metal which chimes when struck contains tin at a high proportion of 25~44%. Statuary bronze contains about 10% of tin and sometimes tin and lead is added. Tin increases hardness, thus only a little amount of it is contained in metals for bearings. Although phosphor bronze, where a little amount of phosphorus is added to bronze to improve quality and strength, contains phosphorus at the small proportion of only 1~2%, it increases strength of equipment like plunger pumps. Manganese bronze which is excellent in mechanical properties contains a little amount of tin but quite a large amount of zinc and manganese. Bronze is used not only for weapons and tools, but also for coinage. ‘Coin’ money is made of bronze which contains tin (about 4%) and zinc (1%).

Since bronze is available for low-temperature processing, it has been used since long ago, and its general use in alloys was so appealing that it offered a firm basis for the growth of metallurgy.

BC

In the Bronze Age, bronze was used for ritual goods (mirrors, bells, etc.) as well as symbolic items denoting power such as the mandolin-shaped bronze daggers of tribal leaders and bronze ritual bells.

Even in the Bronze Age, bronze was not used for farming tools or tools for practical use, but mostly used for weapons, garments and ornaments because bronze is too brittle. It would be of no use as a hoe for plowing a field full of stones. But the bigger problem was that the sources of bronze, copper and tin, were more difficult to obtain than iron which began to be used later, which made bronze too expensive to be used for farming tools.

Although materials for bronze are less abundant and worse in terms of strength than iron, it is high in tensile strength (which means it is not easy to break) and is not eroded by water, thus is commonly used as a material for bronze statues, bells and ordnances. For example, the Emillejong Bell that was fashioned in the era of Silla, retained its original shape for more than a thousand years and the bell was used for several hundred years. If the bell had been made of iron, it would have been ruined and become scrap iron.

Since bronze is a type of alloy, it can have various properties depending on its combination or refining method. Tin is contained at the proportion of not more than 15% in general, but there are some cases like making brass-wares, where it is contained at the proportion of 20~30%. Flexibility increases as the amount of copper increases, and hardness increases as the amount of tin increases. The color of an alloy becomes reddish as the amount of copper increases.

Brass appeared to be green in works of art, so people often take the color of brass as green. The first letter of the Chinese word for bronze (靑銅), '靑', which represents green, was chosen as part of the name for bronze for this reason, but it is the color of rust as a matter of fact. When copper is oxidized, it becomes green. Copper is not generally eroded, but it can be intentionally eroded under special conditions. The most famous piece of sculpture made of oxidized bronze to have a green color in modern times is the Statue of Liberty. Its original color was brown, but now, as is familiar to us all, it appears to be green due to oxidation.

Type Code Chemical Composition (Mass%) Tensile strength
(N/mm2)		 JIS ASTM
    Cu Sn Pb Zn Fe Ni P Al Mn STD No. Designation STD No. Designation
BC1(Type1) CAC401 79.0~83.0 2.0~4.0 3.0~7.0 8.0~12.0 0~0.35 0~1.0 0~0.5 0 0 165 H5111 BC1 B505 C84400
BC2(Type2) CAC402 86.0~90.0 7.0~9.0 0.5~0.8 3.0~5.0 0~0.2 0~1.0 0~0.5 0 0 245 H5111 BC2 B505 C90300
BC3(Type3) CAC403 86.5~89.5 9.0~11.0 0.5~0.8 1.0~3.0 0~0.2 0~1.0 0~0.5 0 0 245 H5111 BC3 B505 C90500
BC6(Type6) CAC406 83.0~87.0 4.0~6.0 4.0~6.0 4.0~6.0 0~0.3 0~1.0 0~0.5 0 0 195 H5111 BC6 B505 C83600
BC7(Type7) CAC407 86.0~90.0 5.0~7.0 1.0~3.0 3.0~5.0 0~0.2 0~1.0 0~0.5 0 0 215 H5111 BC7 B505 C92200
Product Name Property of Alloy Use
CAC401(Type1) Good in terms of machinability and good for brazing and soldering Components of water faucets, bearings, nameplates, components of general machines, etc.
CAC402(Type2) Good in terms of pressure resistance, wear resistance, corrosion resistance and mechanical properties Bearings, sleeves, bushes, body of pumps, impellers, valves, gears, portholes for ships, components of motor devices, etc.
CAC403(Type3) 내압성Good in terms of pressure resistance, wear resistance and mechanical properties and better in terms of corrosion resistance than CAC402 Bearings, sleeves, bushes, body of pumps, impellers, valves, gears, portholes for ships, components of motor devices, components of general machines, etc.
CAC406(Type6) Good in terms of pressure resistance, wear resistance, machinability and castability BearingsValves, bodies of pumps, impellers, feed-water valves, bearings, sleeves, bushings, components of general machines, castings for landscapes, castings for artworks, etc.
CAC407(Type7) Better in terms of mechanical properties than CAC406 Bearings, components of small-size pumps and general machine components