Material Data & Engineering Selection Guide

PB2 Phosphor Bronze (AS 1565 C90810): Mechanical Properties, Equivalents and Application Guide

A structured reference for PB2 phosphor bronze castings — chemical composition, mechanical and physical properties, international grade equivalents, and an application-position matrix covering bushes, bearings, worm gears and pump/valve components.

1. What is PB2 phosphor bronze

PB2 is a high-tin phosphor bronze casting alloy, identified in the source specification as PB2, AS 1565 Grade C90810 and supplied as sand and chill castings. The alloy is a copper–tin system with deliberate residual phosphorus, sometimes written as “Phos Bronze”. It is not a leaded gunmetal; under the AS 1565 C90810 grade its lead upper limit is 0.25 percent.

PB2 combines good machining properties, high strength, shock resistance and good corrosion resistance to seawater and brine. These characteristics make it suitable for pump and valve components, for bearings subjected to medium to high loads and speeds with impact or pounding, and for heavy-duty gears and worm wheels running under adequate lubrication and alignment.

2. Grade equivalence and designation mapping

3. Why PB2 is selected

• Corrosion resistance — good resistance to seawater and brine supports marine and pump/valve service.
• Load and impact performance — suitable for medium to high loads and speeds, with resistance to impact loading or pounding.
• Wear behaviour — high tin content gives good wear resistance in sliding contact against hardened steels.
• Machinability — machinability rating of 30 on a free-cutting brass = 100 basis, workable with conventional tooling.
• Castability — available as sand and chill castings; centrifugal or continuous routes yield higher strength.

4. Chemical composition

Values are maxima unless a range is shown, per AS 1565 C90810. Basis: Standard (requirement of the cited specification).

5. Mechanical properties (typical)

Values are Typical (manufacturer-published indicative values, not minimum requirements) split by casting method. Use the lower figure for screening where conservative design is needed.

6. Physical and process properties

7. Application-position matrix

The matrix maps equipment and service conditions to the component position, load/speed regime, environment, lubrication need and the PB2 form typically selected. Quantitative PV limits are not stated here because they depend on design, surface finish, lubrication and supplier test data.

8. Quick selection guide

9. Sand cast vs chill cast — variant comparison

10. Maintenance and replacement highlights

• Lubrication is required. PB2 is not a self-lubricating (graphite/PTFE) material; bearings must have adequate lubrication and alignment by design.
• Inspect for misalignment, inadequate oil film, abrasive ingress and excessive wear depth.
• Replace when radial clearance, scoring or dimensional wear exceeds the design limit, or when pounding/impact noise indicates loss of the supporting film.
• Stress relief at 260 °C for 1 hour per 25 mm of section reduces residual stress after rough machining of large parts.

11. Engineering checklist

• State the controlling grade precisely: AS 1565 C90810 or BS 1400 PB2 (note the lead / phosphorus limit difference).
• Specify casting method (sand vs chill) — it changes tensile strength by roughly 20%.
• Require an EN 10204 inspection document (2.1 or 3.1) plus chemical certificate.
• Confirm adequate lubrication and alignment in the assembly design.

12. Frequently asked questions

What is PB2 phosphor bronze and how does it differ from PB1?

PB2 is a high-tin phosphor bronze casting grade identified in the United Kingdom as BS 1400 PB2 and in Australia as AS 1565 C90810 (UNS C90810). It is a copper–tin–phosphorus alloy with a tin content of about 11.2 to 13.0 percent. PB1 (CuSn11P, EN CC481K) is a related but distinct grade with slightly lower tin. PB2 is not a leaded gunmetal; under AS 1565 C90810 its lead upper limit is 0.25 percent.

What are the typical mechanical properties of sand-cast and chill-cast PB2?

Typical indicative values are: tensile strength 220 MPa for sand cast and 270 MPa for chill cast; elongation 5 percent for sand cast and 3 percent for chill cast; 0.2 percent proof stress 130 MPa for sand cast and 170 MPa for chill cast; Rockwell B hardness 75 for sand cast and 100 for chill cast. Values vary with casting method, section thickness and test location.

In which applications is PB2 used as a bearing or wear material?

PB2 is used for bushes and bearings, worm gears and heavy-duty gears, pump and valve components, wear rings, crusher bearings, rock-drill parts, marine fittings, rollers, washers, flanges and irrigation equipment. It is selected where medium to high load and speed, impact or pounding resistance, and corrosion resistance to seawater and brine are required. PB2 bearings require adequate lubrication and alignment by design.

13. Disclaimer

Material property data presented here is provided as a data source for engineering evaluation only and does not constitute an airworthiness finding, a certification basis, or any other certification conclusion. Values are indicative and reflect typical published data for PB2 / AS 1565 C90810 / BS 1400 PB2 castings; actual properties vary with casting method, section thickness, chemistry and test location. This document contains no conclusion for military or defence, automotive, food contact, medical, nuclear, or aviation airworthiness applications. It is not a substitute for a supplier material certificate, an EN 10204 inspection document, or sector-specific approval. Verify all values against the controlling specification and the supplied lot test report before use. No warranty of fitness for any particular purpose is made or implied.