Manganese Bronze Alloys

The term bronze is applied to alloys of metal that are copper-based where phosphorus, manganese, aluminum or silicon as the main alloying ingredient.

The primary traits of bronze alloys are that of toughness, strength, corrosion resistance, electrical conductivity, and thermal conductivity. Depending on the alloy, there is a bronze for just about every application.

Bronzes are typically very ductile alloys. By way of comparison, most bronzes are considerably less brittle than cast iron. Typically bronze only oxidizes superficially; once a copper oxide (eventually becoming copper carbonate) layer is formed, the underlying metal is protected from further corrosion. This can be seen on statues from the Hellenistic period. However, if copper chlorides are formed, a corrosion-mode called “bronze disease” will eventually completely destroy it. Copper-based alloys have lower melting points than steel or iron and are more readily produced from their constituent metals. They are generally about 10 percent denser than steel, although alloys using aluminum or silicon may be slightly less dense. Bronze is a better conductor of heat and electricity than most steels. The cost of copper-base alloys is generally higher than that of steels but lower than that of nickel-base alloys.

Cast bronze alloys have been used for centuries in a broad spectrum of bearing applications. Other bearing materials have been unable to match their versatility. By alloying copper with other elements, the properties of bronze can be altered to suit requirements of most any application. The choice of a bronze alloy for a particular application is determined by the desired physical, mechanical and metallurgical properties needed.

A wide selection of bronze alloys is available for industrial and structural applications.

Manganese Bronze is a copper-zinc based alloy, containing small amounts of manganese, aluminum and iron. The right combination of these alloying elements increases the strength of the material. Manganese Bronzes are most commonly used in applications that require some corrosion resistance, anti-seizing properties, coupled with high strength. Manganese bronzes are modifications of the Muntz metal-type alloys (60% copper 40% zinc brasses) containing small additions of manganese, iron and aluminum, plus lead for lubricity, anti-seizing and embeddibility. Like the aluminum bronzes, they combine very high strength with excellent corrosion resistance. Manganese bronze bearings can operate at high speeds under heavy loads, but require high shaft hardnesses and nonabrasive operating conditions.

Typical applications include high load bearings, bushings and gears, gibs, screw down nuts, bridge pins, valve stems and hydraulic cylinder parts. The various types of manganese bronze are a popular choice for the aerospace, fastener, marine, and oil and gas Industries. Typical applications in these industries include landing gear parts, strut bushings, screw machine parts, bearings, bushings, gears, and lead screw nuts.

Table 1: Manganese Bronze alloy properties

Figure 1: Manganese bronze product