An Overview of Phosphor Bronze Alloy

Phosphor bronzes, the main group of engineering alloys, are known for their toughness and strength along with high corrosion resistance and exceptional plating and spring properties. They are alloys of copper with 3.5-10% tin and phosphorus content of up to 0.4%, which is added as a deoxidizing agent during the melting process.

Phosphor bronze alloys are used widely for electronic and electrical components, marine hardware, connectors, valve spindles, fasteners, bearing bushes, gears, pump and drive shafts, instrumentation components and many other important applications where the specific blend of mechanical properties, oxidation and corrosion resistance, spring properties, wear-resistance and low magnetic permeability can be used to maximum advantage.

Columbia Metals stocks a number of the leading grades of phosphor bronze in round bar, sheet, hexagon, and square.

PB102 / CW451K / C51000

The standard grade of wrought phosphor bronze is PB102, which contains additions of up to 0.4% phosphorus and about 5% tin.

It is used for general purpose applications, mainly when cold formability integrated with good mechanical properties is needed, and has superior brazing, soldering, and butt welding capability. PB102 is frequently used as a fastener material and for valve and pump spindles, flanges, springs, shafts and masonry fittings.

PB103 / CW452K

PB103 is mainly a sheet grade and has good wear, strength, and corrosion resistance.

The alloy is used for electrical and mechanical springs and for decorative purposes such as counters, bar tops and other architectural metalwork including masonry fittings and nameplates. PB103 is well-known for its outstanding tarnish resistance and can be used in a broad range of waters and chemicals such as textile and paper manufacturing plants.

PB104 / COLBRONZE / CW453K / C52100 / BS B24

With a higher tin content (8%) than PB102, PB104 is suitable for higher strength and more exacting applications.

It offers excellent wear, bearing and spring properties coupled with superior fatigue performance and corrosion fatigue resistance in marine and other corrosive environments. In particular, PB104 is suitable for high-performance gears, shafts, spindles and bearing components.

COLPHOS 90 / C54400

This grade of material is usually described as the Machinist’s friend. It is a decisive success story in the history of phosphor bronze. COLPHOS 90 has machining features that are nearly indistinguishable from CZ121 brass - the yardstick for free machinability in copper-based materials.

This makes COLPHOS 90 the perfect phosphor bronze grade for complex components. The corrosion resistance and strength of the material are similar to PB102. The addition of 4% lead, dispersed across the matrix, enables exceptional self-lubrication which makes the alloy ideal for bearing bushes and a number of applications where full lubrication cannot be guaranteed.

Stocked sizes of phosphor bronze
PB102 3/32” – 5” dia
3/8” – 2.3/8” A/F
PB103 10 g – 20 g
PB104 1/4” – 2.1/2” dia
COLPHOS 90 1/8” – 2.1/2” dia
5/32” – 1.1/4” A/F
10 g – 16 g

Square also available

Download the Specification Sheet for More Information

This information has been sourced, reviewed and adapted from materials provided by Columbia Metals Ltd.

For more information on this source, please visit Columbia Metals Ltd.


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