C52100 is the ~8% tin phosphor bronze known in Europe as CuSn8 (EN CW453K, Werkstoff 2.1030). It is the material most wrapped bronze bushings are rolled from, and the default choice where a bushing needs high fatigue strength in a thin wall. This page is the specification reference: composition, mechanical properties by temper, bearing load and PV limits, available forms and fits, and the cases where a different alloy should be chosen instead.

How this page differs from our other phosphor bronze pages. Here we cover the material specification — what C52100 is, what it measures, and how to size a bearing in it. If you want phosphor bronze bearings by product form and application, see phosphor bronze bearings. For the alloy family as a whole, see bronze bushing materials.

One correction up front. C52100 is sometimes listed as phosphor bronze “8% C”. The figure refers to 8% tin (Sn), not carbon — C52100 contains no carbon as an alloying element. Any enquiry quoting “8% carbon bronze” is referring to this alloy.

What C52100 phosphor bronze is

C52100 is a wrought copper–tin–phosphorus alloy. The tin provides solid-solution strengthening, and the small phosphorus addition deoxidises the melt and raises stiffness and fatigue strength. The result is a bronze with higher strength and considerably better spring characteristics than the leaded bearing bronzes, at the cost of lower conformability.

Two properties follow from that, and they explain almost every application decision:

• No lead. C52100 does not embed dirt the way C93200 does. It wants clean lubricant and a hard shaft.
• High elastic spring-back. This is precisely why it is the material of choice for wrapped bushings: after rolling and pressing into a housing, the strip springs back against the bore and generates the interference fit without any additional fixing.

It is a wrought alloy, not a casting alloy. C52100 is supplied as strip, bar, plate and tube. It is not produced as a sand or centrifugal casting — where a cast high-tin bronze is needed, the specification moves to casting alloys such as C90700 or C91700. If a drawing calls for “cast C52100”, that is worth querying before manufacture: it usually means either CuSn8 wrought stock machined from bar, or a genuinely cast high-tin bronze that should be named differently.

Chemical composition and international equivalents

The composition limits below are those for C52100 in wrought product form. Copper is the balance; the phosphorus figure is deliberately a band rather than a point, because it is set by the deoxidation practice rather than by a mechanical property requirement.

Table 1 — C52100 nominal composition (wt %, ASTM B103 limits)

Element	Content	Role in the alloy
Copper (Cu)	Balance	Matrix. Carries thermal and electrical conductivity.
Tin (Sn)	7.0 – 9.0	Principal strengthener. Raises strength, hardness and wear resistance.
Phosphorus (P)	0.03 – 0.35	Deoxidiser. Raises stiffness and fatigue strength.
Zinc (Zn)	≤ 0.20	Residual.
Iron (Fe)	≤ 0.10	Residual; controlled to avoid hard inclusions.
Nickel (Ni)	≤ 0.20	Residual.
Lead (Pb)	≤ 0.05	Residual only — the alloy is essentially lead-free.

Table 2 — Cross-reference to other designation systems

System	Designation	Note
UNS / ASTM	C52100	Covered by ASTM B103 (plate, sheet, strip) and B139 (rod, bar, shapes).
EN / DIN	CuSn8, CW453K, Werkstoff 2.1030	The designation used on most European drawings.
BS (legacy)	PB104	Still appears on older British drawings.
JIS	C5210	Close match on tin content.
GB	QSn8-0.3	Chinese equivalent, 8% Sn with 0.3% P.

C52100 and CuSn8 — near enough, but check the temper. The composition ranges overlap, so the two are treated as equivalent for most purchasing purposes. The difference that matters is delivery condition: European CuSn8 strip is normally ordered to a defined EN temper, while a US C52100 order may specify only the alloy. If fatigue life or spring-back is critical to the part, specify the temper, not just the alloy.

Mechanical properties by temper

C52100 is almost always supplied in a work-hardened temper, and the spread between annealed and spring temper is large — tensile strength roughly doubles across the range while elongation falls by an order of magnitude. Specifying “C52100” without a temper leaves the supplier to choose, and the choice changes the part’s behaviour.

The bands below are the EN 1652 delivery tempers (the certified figures when material is ordered to a European mill specification). The ASTM temper names are shown alongside for orientation; the two systems do not map one-to-one, so confirm which system the certificate will quote before releasing the drawing.

Table 3 — Mechanical properties by temper (wrought strip and bar)

EN temper	Nearest ASTM temper	Tensile, Rm (MPa)	Yield, Rp0.2 (MPa)	Elongation A50 (%)	Hardness (HV)
R370	Annealed (O60)	370 – 450	≤ 300	≥ 50	90 – 120
R450	Quarter hard (H01)	450 – 550	≥ 280	≥ 20	135 – 175
R540	Half hard (H02)	540 – 630	≥ 460	≥ 13	170 – 200
R600	Hard (H04)	600 – 690	≥ 530	≥ 5	190 – 220
R660	Extra hard (H06)	660 – 750	≥ 620	≥ 3	210 – 240
R740	Spring (H08)	≥ 740	≥ 700	≥ 2	≥ 230

On elongation figures in circulation. Values as high as 70% elongation are sometimes quoted for C52100. That figure is not representative of the alloy in any temper we supply: it sits above the annealed range and roughly an order of magnitude above the value for spring temper. Design against the row in Table 3 that matches the temper on your order, not against a single headline number.

Which temper for a bushing? Wrapped strip is normally supplied in a hard or spring temper, because the wall has to carry the press-fit load and spring back against the housing — that is the fit mechanism. Annealed material is used where the part has to be formed severely after supply. A machined-from-bar bushing is usually ordered in a half-hard to hard temper, which machines predictably and still has useful strength.

Physical and thermal properties

Table 4 — Physical and thermal data (typical values at room temperature)

Property	Value	Why it matters in a bearing
Density	8.80 g/cm³	Mass and centrifugal load at speed.
Melting range	≈ 880 – 1030 °C	Well above any bearing service temperature.
Thermal conductivity	≈ 67 W/m·K	Carries frictional heat out through the housing.
Electrical conductivity	≈ 13 % IACS (soft condition)	Relevant only where the part also conducts current.
Modulus of elasticity	110 – 115 GPa	Sets spring-back, and therefore the interference generated on fitting.
Coefficient of thermal expansion	18.5 × 10-6 /K (20–300 °C)	Clearance lost as the assembly warms up.
Specific heat	≈ 377 J/kg·K	Thermal mass in intermittent duty.
Poisson’s ratio	≈ 0.34	Secondary; used in FEA models of the fitted assembly.

Two of these numbers matter most. The modulus sets the spring-back that creates the interference fit, so it is the number that determines whether a wrapped bush will hold without adhesive or dowels. The thermal-expansion coefficient is roughly 40% higher than that of steel, so a warm assembly loses running clearance; on a bore above about 80 mm with more than 40 °C of temperature swing, calculate the closure before fixing the as-rolled bore tolerance.

Why C52100 dominates wrapped bronze bushings

A wrapped bushing is rolled from strip. That single manufacturing fact selects the alloy more than any other consideration, and C52100 satisfies four requirements at once.

1. It rolls without cracking. The alloy takes severe cold work in the annealed or lightly worked condition, so strip can be rolled to a small diameter relative to its thickness. Higher-tin bronzes are stiffer and less forgiving at the seam.
2. It springs back, and that is the fit. After rolling and after pressing into the housing, the strip tries to return to its former curvature. Held by the housing, that spring-back becomes a continuous radial pressure against the bore — the interference fit is generated by the material, not by a tolerance on the outside diameter. This is why a wrapped bush stays put without adhesive, dowels or retaining features.
3. It carries the wall load in thin section. Wrapped bushes run at 1–3 mm wall. At that thickness the wall stress is high, and the fatigue strength of a hard-temper C52100 is what lets it survive the press fit plus the service load plus the vibration that would work-harden and crack a softer alloy.
4. It is lead-free. No lead means no restriction under RoHS or ELV, and no concern where the bearing is in contact with potable water or food-processing equipment. For European enquiries this is frequently the deciding factor rather than a mechanical property.

Where the trade-off bites. Because it contains no lead, C52100 has low embeddability: a particle of grit that gets into the contact is not absorbed into the surface, it scores the shaft. That is acceptable in a sealed gearbox and a problem in an open pivot on a construction machine. In dirty service with uncertain lubrication, a leaded bearing bronze will usually outlast C52100 despite its lower strength — the alloy selection and the lubrication regime have to be decided together. See our wrapped bronze bushings page for the forming process and seam types.

Bearing design data

The figures below are for oil- or grease-lubricated C52100 running against a hardened steel shaft. They are starting points for sizing, not design allowables: achievable values depend on the counterface finish, how well heat leaves the housing, and the duty cycle.

Table 5 — Indicative bearing limits for lubricated C52100 / CuSn8

Parameter	Value	Condition
Maximum dynamic load	60 – 90 MPa	Steady, well-lubricated, adequate heat dissipation
Maximum static load	≈ 120 MPa	Stationary or very slow
Maximum sliding speed	2.0 – 2.5 m/s	Continuous, oil-lubricated
PV limit, continuous	1.6 – 2.0 MPa·m/s	Full film lubrication
PV limit, short peaks	up to ≈ 2.8 MPa·m/s	Brief overloads only
Continuous service temperature	up to ≈ 150 °C	Strength falls off progressively above this
Minimum shaft hardness	150 HB (HRC 45 or above recommended for full life)	Softer shafts wear before the bush does
Shaft surface finish	Ra 0.4 – 0.8 µm	Rougher shafts raise friction and wear

Worked example — checking a wrapped bush

A wrapped C52100 bush, 40 mm bore × 40 mm long, carries a radial load of 8 kN at 200 rpm.

• Projected area. For a radial bearing the load is taken on the projected area, A = bore × length = 40 × 40 = 1 600 mm².
• Pressure. P = F / A = 8 000 / 1 600 = 5.0 MPa — well inside the dynamic limit, so load alone is not the constraint.
• Sliding velocity. V = π × D × n / 60000 = π × 40 × 200 / 60000 = 0.42 m/s.
• PV. 5.0 × 0.42 = 2.1 MPa·m/s — slightly over the continuous band of 1.6–2.0, so the bush would run hot in sustained duty even though the load looks comfortable.
• Reading the result. The cheap fix is length, not material: at 50 mm long the pressure falls to 4.0 MPa and PV to 1.68, inside the band. If the length cannot change, the alternatives are to improve heat dissipation from the housing or to reduce the surface speed. Changing to a stronger alloy would not help — the limit here is thermal, not strength.

Duty cycle overrides the steady-state numbers

Frequent starts and stops, reversing load, shock and misalignment all push the effective duty above the calculated figure. Where the duty is severe, size against the lower end of each band and tell us the cycle when you enquire.

Where C52100 must not be used

This section exists because the alloy is frequently specified for duties it cannot serve, and the failure is predictable in each case. All three are worth settling before the drawing is released.

Dry-running duty

C52100 is not a self-lubricating alloy. It is a high-strength bearing bronze that requires a supplied film of oil or grease. Where an application genuinely cannot be lubricated — an inaccessible pivot, a submerged gate trunnion, a food line that must stay dry — the correct specification is a solid-lubricated material rather than C52100. Two routes exist. One is a graphite-plugged bronze, where plugs set into the sliding face transfer a solid film to the shaft and the bearing then runs dry. The other is a C52100 bush with a graphite-plugged or polymer-lined surface where the requirement is intermittent rather than continuous. Specifying plain C52100 for a dry-running duty is the most common way this alloy fails.

Ammonia, hydrogen sulphide and cyanide service

Copper–tin bronzes are not resistant to ammonia, hydrogen sulphide, cyanide or halide solutions, and they are attacked by oxidising acids. Published mill data for CuSn8 lists ammonia and hydrogen sulphide explicitly among the media the alloy does not tolerate. In practice this rules C52100 out of three groups of applications that otherwise look suitable:

• Ammonia refrigeration compressors — the refrigerant attacks the bronze. Specify a steel-backed or aluminium-based bearing material instead.
• Sewage, sludge and pulp handling — hydrogen sulphide from biological activity corrodes the bearing surface.
• Chlorinated or halide-bearing process water — pitting begins at the grain boundaries and the surface breaks up rather than wearing evenly.

What the alloy is good for, on the corrosion side, is natural and industrial atmospheres, maritime air, drinking and service water at moderate flow rate, seawater, neutral saline solutions, alkaline solutions and non-oxidising acids. If your medium is not on that list, tell us the chemistry when you enquire rather than after the first prototype.

Dirty service with uncertain lubrication

An open pivot on earthmoving or agricultural equipment sees grit, water and irregular greasing. The low embeddability of a lead-free alloy means the grit is not absorbed, and the shaft scores. Leaded bearing bronze or a cast alloy such as C93200 will usually give longer service here, at lower strength. Where load is also high and the atmosphere is corrosive, the specification moves further up to C95500 nickel aluminum bronze.

How C52100 compares with other bearing bronzes

Table 6 — C52100 against the common alternatives

Property	C52100 (CuSn8)	C93200 (SAE 660)	C51000 (CuSn5)	C95500 Ni-Al bronze
Product form	Wrought strip, bar, plate	Cast and machined	Wrought strip	Cast and machined
Tin	7 – 9 %	≈ 7 %	≈ 5 %	—
Lead	None	6 – 8 %	None	None
Tensile, typical	520 – 900 MPa	≈ 240 – 310 MPa	400 – 760 MPa	620 – 760 MPa
Fatigue strength	High	Moderate	High	High
Embeddability	Low	High	Low	Low
Lubrication demand	Needs clean, reliable oil	Tolerates marginal lubrication	Needs clean oil	Needs reliable oil
Typical use	Wrapped bushes, thin walls, springs, thrust washers	Solid machined bushes, dirty service	Electrical contacts, lighter springs	Heavy solid bearings, marine

Choose C52100 where the wall is thin, the section has to spring, the lubrication is reliable, and lead-free compliance matters — wrapped bushes and thrust washers above all.

Choose C93200 where the environment is dirty, alignment is uncertain, or the bearing is thick-section and machined solid; its lead content buys tolerance that C52100 does not have.

Choose C51000 where conductivity or formability matters more than strength.

Choose C95500 where load and corrosion resistance both run high, as in marine and heavy mill equipment — see C95500 nickel aluminum bronze.

Available forms, sizes and fits

Table 7 — Forms we work in and indicative size ranges

Form	Indicative range	Typical finished part
Strip and coil	Thickness 0.5 – 3.0 mm	Wrapped bushes, rolled to order
Wrapped bushes	Bore 6 – 300 mm, wall 1 – 4 mm	Standard and non-standard wrapped bearings
Solid bar	Diameter 8 – 300 mm	Machined bushes, wear rings
Plate and flat bar	Thickness 3 – 50 mm	Wear plates, slide plates, thrust washers
Tube and sleeve	OD 20 – 300 mm	Long sleeves, large diameter bushes

Fits

For a wrapped bush the housing bore is normally H7 and the bush outside diameter is produced with an interference — commonly an r6 or s6 field — so that the finished assembly is tight without distorting the bore excessively. After pressing, the bore closes by a large proportion of the outside-diameter interference; expect the running clearance to be set by that closure rather than by the as-rolled bore, and finish the bore by machining or burnishing after fitting where the tolerance is tight. Shaft fits are typically f7 or g7 against the finished bore, with the clearance chosen after allowing for the thermal expansion of both parts.

Measuring thin-walled parts needs care, since a wall will deflect under the measuring force — see reading and measuring of bearing tolerance.

Oil grooves

C52100 bushes are usually supplied with a groove pattern rolled or cut into the bore, since the alloy depends on a supplied lubricant film. Diamond, figure-eight, circular and straight patterns are all used, and the pattern has to suit the direction of rotation. Options are set out on our bush groove patterns page.

Machining and handling notes

C52100 is a work-hardening alloy with low machinability: published mill data for CuSn8 rates it as not recommended for general machining, and its cutting performance is roughly 20–30% that of free-cutting brass. It can be machined well, but only with the right approach. Cuts must be continuous and feeds kept positive, because the surface work-hardens if a tool is allowed to dwell, and the hardened layer then destroys the next pass. Use sharp tooling with a positive rake, generous depth of cut, and no spring passes.

Thin-walled parts deflect under tool pressure and under the jaws of a chuck or vice — use a backing plate or a full-length support, and take a finishing cut rather than forcing the wall. When drilling, bronze tends to grab on breakthrough: use a sharp drill with reduced rake, peck to clear the flutes, and clamp the work. Capability and tolerances for finished parts are on our CNC machining of bronze page.

Spring-back on formed parts. Anything rolled or bent from C52100 strip will open out slightly after forming. The allowance depends on the temper and the bend radius, and it is built into the tooling rather than corrected afterwards. If you are forming parts in-house from our stock, tell us the temper and we will give you the spring-back figure to work to.

Typical applications

Wrapped bushes are the largest use by volume: agricultural machinery pivots, construction equipment linkages, material handling rollers, and automotive chassis and suspension points. The combination of thin wall, spring fit and fatigue strength suits these duties directly. Crane applications are covered separately under wrapped bushings in crane service.

Thrust washers and wear plates use C52100 where the load is moderate and reliability of lubrication is good — gearbox thrust faces, pump wear rings, and machine tool slide plates. See bronze thrust washers and bronze guide sliders.

Marine and pump hardware uses the alloy for its corrosion resistance in seawater, in impeller wear rings, shaft sleeves and valve trim. Above roughly moderate loads, the nickel aluminum bronzes take over.

Outside bearings, C52100 is widely used for springs, contacts and switchgear components — a consequence of the same spring temper and fatigue strength. We do not supply those; our work is the bearing and wear part side of the alloy.

Frequently asked questions about C52100 phosphor bronze

Is C52100 the same as CuSn8?

For most purchasing purposes, yes. CuSn8 is the European designation (EN CW453K, Werkstoff 2.1030) and C52100 is the UNS designation; the composition ranges overlap. The practical difference is delivery condition: CuSn8 strip is normally ordered to a defined EN temper such as R540 or R660, while a C52100 order may name only the alloy. If fatigue life or spring-back matters, specify the temper, not just the alloy.

Can C52100 be used without lubrication?

No. C52100 requires a supplied film of oil or grease and is not a self-lubricating material. For dry-running duty, use a graphite-plugged bronze or a polymer-lined composite instead. Specifying plain C52100 in a dry application is the most common way this alloy fails in service.

Why does C52100 score the shaft in dirty service?

Because it contains no lead. C93200 and other leaded bearing bronzes embed abrasive particles into the soft lead phase, so the grit stops cutting the shaft. C52100 has no such phase, so a particle trapped in the contact zone keeps cutting. The trade-off is deliberate: the same lead-free composition is what makes the alloy compliant with RoHS and ELV and acceptable in potable-water and food-contact equipment.

Is C52100 resistant to seawater and to ammonia?

Seawater, yes — the alloy resists seawater, neutral saline solutions, maritime atmospheres and non-oxidising acids, which is why it appears in pump wear rings and marine shaft sleeves. Ammonia, no. Copper–tin bronzes are not resistant to ammonia, hydrogen sulphide, cyanide or halide solutions, so C52100 should not be specified for ammonia refrigeration compressors, sewage or sludge handling, or chlorinated process water.

What temper should I specify for a wrapped bushing?

Hard or spring temper (R600 to R740, or ASTM H04 to H08). The wall has to carry the press-fit load and then spring back against the housing to generate the interference fit, and that mechanism depends on a high yield strength. Annealed material is only appropriate where the part must be formed severely after delivery.

Can C52100 be cast?

No — it is a wrought alloy, supplied as strip, bar, plate and tube. Cast high-tin bronzes such as C90700 and C91700 cover the casting route. If a drawing requests “cast C52100”, it usually means either CuSn8 wrought stock machined from bar, or a different cast alloy that should be named on the drawing.

Specifying C52100 — what we need from you

Send the load, speed, shaft specification and duty cycle. We will confirm whether C52100 is right, or say plainly if a leaded bronze or a graphite-plugged one would give longer service. For a firm quotation, include:

1. Bore and length, with the housing bore tolerance and the shaft fit class.
2. Wall thickness, or the housing bore and outside diameter if the bush is rolled to fit.
3. Temper, if fatigue life or spring-back is critical; otherwise state the load case and we will recommend one.
4. Operating environment: lubricant type, whether water or process fluid reaches the bearing, and the temperature range.
5. Quantity for the prototype and the annual volume, and any compliance requirement (RoHS, ELV, potable water, food contact).

Full material and tolerance capability for finished parts is on our CNC machining of bronze page. To discuss a specific duty, contact us with the drawing or the sample.