Bronze Alloys

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

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

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

PB102 / CW451K / C51000

PB102 is the standard grade of wrought phosphor bronze, with additions of around 5% tin and up to 0.4% phosphorus. It is used for general purpose applications, specifically when cold formability along with good mechanical properties is needed, and has exceptional brazing, soldering and butt welding capability. PB102 is frequently used as a fastener material and also for pump and valve spindles, flanges, springs, shafts, and masonry fittings.

PB103 / CW452K

PB103, primarily a sheet grade, offers good strength, wear and corrosion resistance. The alloy is used for electrical and mechanical springs and also for decorative purposes such as counters, bar tops and various other architectural metalwork including masonry fittings and name plates. PB103 is well-known for its exceptional tarnish resistance and can be used in an extensive range of chemicals and waters such as textile and paper manufacturing plants.

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
Square also available

 

PB104 / COLBRONZE / CW453K / C52100 / BS B24

With a greater tin content (8%) than PB102, PB104 is considered to be perfect for higher strength and additional exacting applications. It offers excellent bearing, wear and spring properties along with exceptional fatigue performance and corrosion fatigue resistance in marine and various other corrosive environments. PB104 is particularly ideal for high performance gears, shafts, spindles and bearing components.

COLPHOS 90 / C54400

Frequently described as the machinist’s friend, this grade of material is considered to be a resounding success story in the history of phosphor bronze. COLPHOS 90 is available with machining characteristics almost indistinguishable from CZ121 brass - the standard for free machinability in copper-based materials. This allows COLPHOS 90 to be the ideal phosphor bronze grade for complicated components. The material’s corrosion resistance and strength are similar to PB102. The addition of 4% lead, dispersed all over the matrix, allows exceptional self-lubrication which enables the alloy to be greatly suitable for bearing bushes and several applications where it is not possible to guarantee full lubrication.

Technical Data

Nominal Composition (%)

  Cu Sn P Pb Zn
PB102 Rem 5.0 0.2 - -
PB103 Rem 7.0 0.2 - -
PB104 Rem 8.0 0.2 - -
COLPHOS 90 Rem 5.0 0.2 4.0 3.0

 

Typical Mechanical Properties (minimum values dependent on size)

  PB102 PB103 PB104 COLPHOS 90
Ultimate Tensile Strength (N/mm2) 350 - 500 460 - 500 450 - 600 350 - 450
0.2% Proof Strength (N/mm2) 280 - 420 380 - 420 320 - 450 250 - 350
Elongation (%) 12 - 25 12 - 18 15 - 20 10 - 15
Machinability Rating 20 20 20 90

 

Round Bar Weight and Stock Sizes

Diameter Weight Diameter Weight Diameter Weight
ins kg/ft kg/m ins kg/ft kg/m ins kg/ft kg/m
0.094 0.01 0.04 20 mm 0.83 2.73 2.250 6.80 22.32
0.125 0.02 0.07 0.875 1.03 3.38 2.500 8.40 27.55
0.156 0.03 0.11 1.000 1.34 4.41 2.625 9.26 30.37
0.188 0.05 0.16 1.125 1.70 5.58 2.750 10.16 33.34
0.250 0.08 0.28 1.250 2.10 6.89 3.000 12.09 39.67
0.313 0.13 0.43 1.375 2.54 8.33 3.250 14.19 46.56
0.375 0.19 0.62 1.500 3.02 9.92 3.500 16.46 54.00
0.438 0.26 0.84 1.625 3.55 11.64 3.750 18.89 61.99
0.500 0.34 1.10 1.750 4.12 13.50 4.000 21.50 70.53
0.625 0.54 1.72 1.875 4.72 15.50 4.500 27.21 89.26
0.688 0.64 2.08 2.000 5.37 17.63 5.000 33.59 110.20
0.750 0.76 2.48 2.125 6.07 19.91 130 mm 35.20 115.47

 

NB Weight data for guidance only.

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