Bronze Alloy Selection
23 October
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Phosphor Bronze PB2
Key Features
- Handles high working loads
- Good for high working speeds
- Suitable for pump and valve components
- Good corrosion resistance to seawater and brine
- Suitable for heavy duty gears and worm wheels
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Key Features
- Handles high working loads
- Good for high working speeds
- Suitable for pump and valve components
- Good corrosion resistance to seawater and brine
- Suitable for heavy duty gears and worm wheels
Overview
PB1 Phosphor Bronze is a high strength material that is often referred to as ‘gear bronze’. Components that are machined from PB2 are particularly durable in applications where high working loads and speeds are encountered, provided that there is good alignment and adequate lubrication. PB1 has good machining properties and good corrosion resistance to seawater and brine, making it suitable for pump and valve components. PB2 is suitable for bearings having medium to high loads and speeds, and has good resistance to impact loading or pounding.
All Kormax PB2 Phosphor Bronze is manufactured using finely controlled continuous or centrifugal casting techniques to ensure that hardness and strength is superior to sand-casting methods. This also means that the material has a fine grain structure and is free from porosity.
Chemical Composition
| Element | Symbol | Range % | Nominal % |
| Tin | Sn | 11.0-13.0 | 11.5 |
| Lead | Pb | 0.50 maximum | |
| Zinc | Zn | 0.30 maximum | |
| Nickel | Ni | 0.50 maximum | |
| Iron | Fe | 0.10 maximum | |
| Aluminium | Al | 0.01 maximum | |
| Phosphorus | P | 0.15-0.6 | 0.35 |
| Copper | Cu | Balance |
Physical Properties
| Material | Unit | Phosphor Bronze PB2 |
| Tensile Strength Min | N/mm2 | 300 |
| Yield Strength Min | N/mm2 | 180 |
| Elongation Min | % | 10% |
| Hardness Min | BHN | 100 |
Machining Allowances
All Kormax PB2 Bronze bar has machining allowances added to the sizes quoted. To use 4-1/2” x 2-1/2” hollow bar as an example, this material would measure approximately 4.570” OD x 2.440” ID as supplied (see table below). This allows finished components measuring 4-1/2” OD x 2-1/2” ID to be easily manufactured from 4-1/2” x 2-1/2” hollow bar.
Machining allowances are as follows:
Outside Diameter
Size Range
up to 3-3/4”
4” to 5”
5-1/4” to 6”
6-1/4” to 20”
Allowance
+0.040”
+0.070”
+0.094”
+0.109”
Inside Diameter
Size Range
up to 3-3/4”
4” to 5”
5-1/4” to 6”
6-1/4” to 18”
Allowance
-0.060”
-0.090”
-0.108”
-0.120”
Comparative Specifications
BS1400 – PB2; AS1565 – 90810; ASTM B427 – C90800 ; SAE 65 *; JIS H5121 – CAC502C (PBC2C) *; DIN 1705 – G – CuSn12; ISO 1338 – CuSn11P