C51900 Phosphor Bronze | CuSn6 Spring Alloy for Electrical Connectors, Relay Contacts & Instrument Springs

C51900 Phosphor Bronze (UNS C51900, EN CW452K, CuSn6), is lead‑free wrought copper‑tin‑phosphorus spring bronze containing 5.5‑7.0% tin and controlled phosphorus 0.03‑0.35%. Phosphorus acts as melting deoxidizer and greatly improves fatigue performance, spring property and wear resistance. Compared with C51000, higher tin content delivers enhanced strength and elastic limit while retaining acceptable formability and electrical conductivity for spring‑type components.

Quick Grade‑Selection Answer For Your Project: Pick C51900 for higher‑strength electrical connectors, relay contacts, instrument diaphragms and repeated‑flex spring parts; choose C51000 if moderate spring performance with better formability is your priority; select C52100 for maximum wear‑corrosion resistance under harsh mild corrosive environment; choose leaded C54400 only for high‑volume CNC‑machined bushing projects (not for spring‑contact applications).

Many buyers make material mistakes: selecting low‑tin C51000 for high‑stress repeated‑cycling springs, or applying lead‑containing C54400 for RoHS‑compliant electronic spring assemblies. As your reliable China factory supplier, HSMetal provides C51900 phosphor bronze in sheet, strip and rod. We support custom cut‑to‑size, with mill test certificate available for every shipment for both R&D sampling and mass‑volume serial production. For chemical‑compatibility knowledge of phosphor bronze under corrosive environment, please visit Read our phosphor bronze chemical‑resistance blog.

Our high-precision C51900 phosphor bronze strip customization capability has been fully verified in actual overseas mass production projects. We successfully delivered 0.65mm 1/2H temper C51900 phosphor bronze strip to a Turkey manufacturer for high-cycle relay spring production, solving strict flatness tolerance and long-term fatigue resistance challenges. For detailed technical optimization process and project results, you can view our C51900 phosphor bronze Turkey export project case news.

C51900 Phosphor Bronze CuSn6 Spring Alloy is a copper-tin alloy containing 5.5–7.0% tin and 0.03–0.35% phosphorus, with the phosphorus acting as a deoxidizer and grain refiner to enhance mechanical properties . It is the standard grade specified in ASTM B103 for phosphor bronze plate, sheet, strip, and rolled bar .

Standards & Equivalents

C51900 Typical Chemical Composition

1. Superior Elasticity for High-Cycle Springs
C51900 Phosphor Bronze CuSn6 Spring Alloy delivers an elastic limit ≥500 MPa and fatigue life exceeding 1 million cycles - significantly higher than C51000 . This makes it the preferred choice for connector contacts, relay springs, and switch elements where spring force must remain stable over years of operation.

2. Excellent Wear Resistance
With hardness ranging from HV 200–300 in hard temper, C51900 Phosphor Bronze CuSn6 Spring Alloy offers wear resistance approaching beryllium bronze performance - without the cost and health concerns of beryllium .

3. Proven Corrosion Resistance
Resistant to atmospheric, seawater, and weak acid corrosion with a corrosion rate ≤0.005 mm/a . This makes C51900 suitable for marine environments, industrial atmospheres, and outdoor electrical equipment.

4. Anti-Magnetic Properties
C51900 Phosphor Bronze CuSn6 Spring Alloy is non-magnetic, making it suitable for precision instruments, 5G RF components, and medical devices where magnetic interference must be avoided .

5. Excellent Solderability & Plating
Supports tin, gold, and silver plating with good adhesion. Tin-plated C51900 (1–6μm) is commonly specified for solderable connector terminals .

We supplied C51900 phosphor bronze strip (1/2H temper) to one industrial component manufacturer from Turkey. The end‑product is high‑reliability relay spring contacts used in household electrical control devices.

Customer requirements:

Material: UNS C51900 phosphor bronze strip, 0.65 mm thickness, 10mm width, 1/2H temper

Key target: Stable spring contact force after over 500 000 flexing cycles; RoHS lead‑free requirement

Deliverables: Custom slit width blanks, full mill test certificate, batch mechanical test records

Challenge: Strict flatness tolerance for progressive stamping production in Turkey local factory.

Our solution & outcome: We controlled rolling and annealing process to guarantee consistent hardness and strip flatness. Custom slit‑to‑width blanks were produced, full MTC documents provided. Goods passed customer incoming lab inspection in Turkey. This batch material has run stable on customer stamping line for relay contact mass‑production without spring‑force‑related failure.

If you have similar high‑cycle spring‑contact projects, share your temper, dimension and cycle‑life requirement; our engineering team can provide targeted material suggestion.

C51900 Phosphor Bronze Strip coil Stock in Warehoue Ready To Ship

C51900 Phosphor Bronze Strip C For Turkey Customer

C51900 Phosphor Bronze Strip  Package As Customer Requirement From HSMetal

If you have similar high‑cycle spring‑contact projects, share your temper, dimension and cycle‑life requirement; reach our engineering team can provide targeted material suggestion.

Standard dimension range

• Sheet / Strip: Thickness 0.1 mm‑10 mm; width up to 1200 mm
• Rod / bar: Diameter 3 mm‑50 mm
• Length & blanks: custom‑cut / custom‑slit according to customer drawings

Our custom capabilities

• Custom cut‑to‑size sheet, custom slit strip, rod segments for prototype and mass‑production
• Multiple tempers customized (from O annealed up to SH extra‑spring temper) matching your stamping / spring‑force requirement
• Surface options: mill finish, brushing
• Small‑batch sample order support; large‑volume serial‑production capacity

Besides C51900, we also supply C51000, C52100, C54400 phosphor‑bronze products for one‑stop material sourcing.

Luoyang Hongsheng Trading Co., Ltd. (HSMetal) is a specialized phosphor bronze manufacturer with a complete in-house production chain covering melting, hot rolling, precision cold rolling, temper annealing, slitting, and custom cutting - purpose-built for C51900, C51000, C52100, and C54400 sheet and strip products.

Our C51900 material is produced and inspected to ASTM B103 / EN 1652 (CuSn6) requirements, with strict control over chemical composition tolerance and full-range laboratory testing on every batch. Each shipment is delivered with a complete Mill Test Certificate and heat number traceability, supporting smooth incoming QC for connector, spring, and 5G terminal manufacturers.

With years of export experience across Turkey, Southeast Asia, and Europe, we understand the documentation, packaging, and delivery requirements of overseas buyers - including pre-cleared HS codes, CE-compliant material, and Turkish-language QC reports on request.

Beyond supplying standard stock and custom cut-to-size blanks for both prototyping and mass production, our material engineering team provides practical technical support: grade selection, temper recommendation for high-cycle springs, and stamping process guidance. We help global customers avoid common material risks - wrong grade selection, unsuitable temper for spring components, and avoidable production downtime - positioning ourselves as a reliable one-stop partner for phosphor bronze alloy solutions.

[Request a C51900 Quote] | [Phosphor Bronze Product Catalog] | [Contact Technical Team]

Our Factory

 

Copper Strip Production Line China Manufacturer HSMetal

Phosphor Bronze Copper Coil Strip Production Line

Brass Strip Slitting Equipment

Vacuum Melting Furnace

Rolling Mill Equipment

Aging Treatment Equipment

Q1: What is the difference between C51900 and C51000?
A: C51900 contains ~6% tin vs ~5% for C51000, giving it higher strength and fatigue resistance (elastic limit ≥500 MPa vs ~450 MPa). C51000 offers better formability and slightly higher conductivity .

Q2: Can C51900 be used in seawater?
A: Yes - C51900 resists seawater corrosion with a rate of ≤0.005 mm/a. For continuous immersion, it is suitable for valve components, sensor parts, and marine connectors .

Q3: Is C51900 the same as CuSn6?
A: Yes. C51900 (ASTM) = CuSn6 (EN) = C5191 (JIS) = QSn6.5-0.1 (GB). They are equivalent grades within normal commercial tolerances .

Q4: Do you supply to Turkey?
A: Yes. We have established export channels to Turkey with pre-cleared documentation and local logistics partners. Typical delivery to Istanbul is 20–30 days including customs.

Q5: What certifications do you provide?
A: Mill Test Certificate (MTC), ASTM B103 compliance, EN 1652 equivalence, and third-party inspection (SGS, BV) on request.

Q6: What temper should I select for high‑cycle relay spring contacts?

A: H or EH temper is widely‑adopted for high‑cycle spring‑contact components. For heavy forming / deep‑drawing process, choose O or 1/4H temper.

Q7: What is the difference between C51900 and C51000?

A: C51900 contains higher tin content, delivering higher strength and elastic limit for high‑stress repeated‑flex springs. C51000 offers better formability for general‑purpose stamping parts with lower strength requirement.

Q8: Is C51900 RoHS compliant?

A: Yes, C51900 is lead‑free phosphor bronze and meets RoHS requirement for electronic assemblies.

Q9: Can you provide C51900 samples for stamping and cycle‑life testing?

A: Yes, custom‑cut strip / sheet samples are available for customer lab evaluation.

Q10: Is Mill Test Certificate provided for each shipment?

A: Yes. Mill test certificate covers chemical analysis, hardness and mechanical‑property test data. Third‑party inspection can be arranged at buyer's cost upon request.

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