SPECIAL BRASS

High Tensile brass

 

High Tensile brass is copper-zinc alloy which combines with additives to increase the tensile strength over that of the simple binary copper-zinc brass.

 

Fitco can produce High Tensile Brass solid and hollow rods.

Properties

This family of alloys exhibit tensile strength in excess of 700N/mm2, along with enhanced properties of wear and corrosion resistance.

The alloys containing aluminium have an attractive, naturally lustrous surface and a protective oxide film for extra corrosion resistance. The silicon-containing alloys with manganese have excellent wear resistance, due to the formation of a very hard intermetallic compound, manganese silicide, in the basic matrix.

Applications

They are suitable for a wide range of applications and service conditions, ranging from decorative architectural use to wear resistant automobile transmission components and the high strength, high integrity equipment used in mines.

EU End of Life Vehicle (ELV) Directive

The EU End of Life Vehicle (ELV) Directive, adopted in September 2000, includes provision for phasing out metals such as lead used in automotive components. Applications for these copper alloys include bearing shells and bushes, nozzles, connection parts, fixtures and locks.

DZR

 

DZR (Dezincification-resistant) brass constitutes the best solution for use in unusually aggressive water supplies. In this environment, conventional duplex brass water fittings can suffer, a form of corrosion known as dezincification. This involves selective leaching of the zinc which can cause fracture of the fitting. Addition of a small amount of phosphorous, arsenic or antimony inhibits the occurrence of the dezincification.

 

Fitco can produce DZR solid and hollow rods and seamless tubes.

Properties

Brass at hot stamping or extrusion temperature, contains sufficient β phase to be hot-worked satisfactorily.The B phase can be converted by subsequent heat treatment to an all-alpha structure which is protected against dezincification by incorporating arsenic in the alloy. Forgeable DZR brass, such as CW602N (CZ132), is leaded brass and its machinability is comparable with the leaded duplex brass CW617N (CZ122). They are commonly used for production of water fittings. Rods and bars for machining are heat treated by the materials supplier to put them into the dezincification-resistant condition. Forging stock is supplied without heat treatment since it must be heated after forging to 500-525ºC, held for at least two hours and slowly cooled, to ensure resistance to dezincification. This has to be done by the fittings manufacturer.  The need for heat-treatment after forging, to ensure an all-alpha structure, can sometimes be avoided by controlled slow cooling through the temperature range 550ºC to 450ºC. Although, this is a more difficult method to achieve the correct degree of dezincification resistance.

Applications

These alloys are used as fittings, stopcocks and valves with a carefully controlled composition, which are made by extrusion or hot stamping. This production process must be followed by heat treatment to ensure that the material will satisfy the requirements of the standard dezincification-resistance test (EN ISO 6509-1). The maximum permitted parameters of dezincification are defined in EN product standards.

Naval Brass

 

Naval Brass has a chemical composition of around 60% copper 39% zinc and 1% tin with an amount of lead. These alloys are included in the family of α and β or duplex brass.  This category of brass exhibit generally higher mechanical properties than other non-duplex brass.

 

Fitco can produce Naval brass solid and hollow rods and sections.

Properties

As its name implies, naval brass is widely used for naval and steam-generating equipment and generally for sea water service applications, where a strong, hard material is required. Tin is included in the alloy composition in order to improve the corrosion resistance of the material. Tin tends to inhibit dezincification. Dezincification is a type of dealloying in which one of constitutes of an alloy is removed by corrosion. In this case, Zn is depleted and results in a porous Cu-rich layer.

The presence of lead in naval brass assists in the machinability of the metal. This subcategory of brass is named leaded naval brass and contains nominally 60% Cu, 1% Sn, 2% Pb and 37%Zn. These alloys have the equivalent strength and corrosion resistance of naval brass plus considerably improved machinability.

Applications

Naval brass is used in propeller shafts, marine hardware, decorative fittings, shafting, propeller shafts and turn buckles. There are also many industrial applications, such as welding rods, condenser plates, structural uses, valve stems, balls, heat exchanger tubes, aircraft turnbuckle barrels, dies, and many more.