C51000 Phosphor Bronze
Balanced conductivity, corrosion resistance and fatigue behavior for contacts and small springs.
Conductive & Non-Magnetic Spring Materials
Copper Alloy Spring Materials
Copper-based spring alloys for electrical conductivity, corrosion resistance, non-magnetic behavior and precision contact components.
MATERIAL FAMILY
- Grades covered
- 5
- Strength
- Medium to very high
- Corrosion
- High
- Temperature
- Low to medium
- Conductivity
- Medium to excellent
Grade Overview
Materials in This Family
Use this page to compare the role of each grade. Final wire size, strength condition, heat treatment and allowable stress are confirmed against the drawing and operating conditions.
C52100 Phosphor Bronze
Higher-strength phosphor bronze for demanding contact springs and stamped components.
C17200 Beryllium Copper
Very high-strength conductive copper alloy for precision contacts and high-cycle spring parts.
C17510 Copper-Nickel-Beryllium
Higher-conductivity beryllium copper family for current-carrying elastic contacts.
C26000 Cartridge Brass
Formable and economical material for light-load contacts, clips and decorative spring parts.
Copper Alloy Spring Material Selection Guide
How to Choose a Copper Alloy for a Spring or Electrical Contact
Copper alloys are selected when a spring must do more than store mechanical energy. Electrical conductivity, contact resistance, non-magnetic behavior, corrosion resistance, plating compatibility and forming direction can be as important as spring force. C51000 phosphor bronze is a practical general contact material, C52100 raises strength, C17200 beryllium copper reaches much higher spring strength, C17510 shifts the balance toward higher conductivity, and C26000 brass is best reserved for lighter-duty, cost-sensitive parts. The correct choice therefore depends on the electrical and mechanical requirement together, not on conductivity alone.
For product geometry and quotation requirements, see Variable-Diameter Compression Springs, Straight-Leg Torsion Springs, German-Hook Extension Springs. These pages include reference configurations from this material family; confirm the exact grade for your project.
Electrical + Mechanical Comparison
Compare Copper Alloy Spring Grades
The key trade-off in copper spring alloys is usually conductivity versus strength, with fatigue, formability, plating and process controls setting the final choice.
| Grade | Best Fit | Corrosion / Contact Environment | Strength / Fatigue Position | Electrical / Thermal Position | Selection Note |
|---|---|---|---|---|---|
| C51000 Phosphor BronzeUNS C51000; ASTM B159/B103 by product form | General connectors, switches, relays, instruments, clips and small springs | Good atmospheric and many water-service environments | Medium spring strength with useful fatigue behavior | Moderate conductivity; suitable for many signal/contact duties | A balanced starting point when you need better corrosion and conductivity than steel without the cost of beryllium copper. |
| C52100 Phosphor BronzeUNS C52100; ASTM B159/B103 by product form | Higher-reliability contacts, stronger stamped springs and precision connectors | High | Higher strength and elastic response than C51000 | Conductivity lower than lower-tin phosphor bronze grades | Choose when spring force and fatigue margin need to increase but the design can accept some conductivity trade-off. |
| C17200 Beryllium CopperUNS C17200; ASTM B197/B194/B196 by product form | High-force contacts, high-cycle springs, aerospace, semiconductor and precision mechanisms | Very high with good plating compatibility | Very high after controlled hardening; among the strongest copper spring alloys | Useful conductivity with much higher strength than phosphor bronze | Premium choice for high spring force plus conductivity. Processing should use qualified beryllium-copper controls, especially for dust-producing operations. |
| C17510 Copper-Nickel-BerylliumUNS C17510; ASTM B441 and product-specific standards | High-current elastic contacts, relays, server hardware and power interconnects | Very high | Medium-high to high; below C17200 in maximum strength | Higher conductivity than C17200 in many hardened product forms | A strong option when current-carrying capacity matters more than maximizing spring strength. |
| C26000 Cartridge BrassUNS C26000; ASTM B134/B36 by product form | Light-load contacts, clips, decorative elastic parts and cost-sensitive formed components | Moderate to good; avoid ammonia-related stress-corrosion conditions | Low to medium; not a high-fatigue first choice | Good conductivity and easy formability | Use when cost and forming are more important than high-cycle spring performance; upgrade to phosphor bronze or beryllium copper as duty increases. |
Engineering Selection
Six Factors That Change the Copper Alloy Decision
For electrical spring parts, mechanical and electrical requirements must be solved together. A stronger alloy can reduce deflection or contact force problems, while a more conductive alloy can reduce temperature rise.
Specify current, voltage and contact function before choosing by alloy name
Signal contacts, grounding springs and high-current power contacts do not need the same conductivity. Contact force, resistance, temperature rise and mating-cycle requirements should be defined before choosing between phosphor bronze, C17200 or a high-conductivity grade.
Strength and conductivity move in opposite directions in many copper alloys
Higher cold work or age hardening increases strength but can reduce conductivity or formability. C17200 favors strength, while C17510 can be a better balance for high-current applications. The selected temper is therefore as important as the UNS grade.
Strip direction, edge quality and bend radius matter for stamped spring contacts
Rolling direction, temper and bend radius strongly influence cracking and springback in flat contacts. Precision slit edges and burr orientation can also affect fatigue and assembly reliability.
Plating is part of the contact system
Tin, nickel, silver or other finishes can change contact resistance, solderability, fretting behavior and corrosion protection. Material selection should be reviewed together with the mating contact and plating stack.
Beryllium copper requires qualified processing controls
Finished beryllium-copper components are widely used in engineering products, but dust-producing machining, grinding or polishing requires appropriate occupational controls and supplier compliance. Select a processor experienced with the alloy and required hardening condition.
Non-magnetic behavior can be a functional requirement
Copper alloys are useful around sensors, instruments and magnetic assemblies because they are generally non-magnetic. If the application has a strict magnetic-permeability requirement, define it on the drawing and verify the finished part rather than relying only on material family.
Fast Selection
Which Copper Alloy Should You Start With?
Use electrical duty, contact force, fatigue life and forming method as the first filters.
| Design Condition | Starting Recommendation | Why |
|---|---|---|
| General signal contact or corrosion-resistant spring contact | Start with C51000 phosphor bronze | Good balance of spring behavior, conductivity, corrosion resistance, formability and cost. |
| Need more force or fatigue margin than C51000 | Evaluate C52100 phosphor bronze | Higher-tin phosphor bronze can provide higher strength with a conductivity trade-off. |
| High spring force + high cycle + electrical function | Evaluate C17200 beryllium copper | Very high hardened strength while retaining useful conductivity and corrosion resistance. |
| High current with elastic contact function | Evaluate C17510 | Designed toward a higher-conductivity balance while still providing useful spring strength. |
| Light-duty clip or cost-sensitive decorative/contact part | Evaluate C26000 brass | Easy to form and economical when high fatigue or high contact force is not required. |
| No electrical requirement; only mechanical spring force | Compare stainless or carbon/alloy steel | Copper alloys may add cost without providing a useful advantage when conductivity and non-magnetic behavior are irrelevant. |
When Conductivity Is Not the Main Driver
Compare Other Spring Material Families
Copper alloys are valuable for electrical and non-magnetic components, but steel, nickel or cobalt families can be more efficient when strength, high temperature or severe corrosion dominates.
Stainless Steel Spring Materials
Choose stainless when corrosion resistance and spring strength matter but electrical conductivity is not required.
Compare this family →Carbon & Alloy Spring Steels
Use steel for the most economical path to high spring force and fatigue performance in protected environments.
Compare this family →Cobalt High-Performance Alloys
Consider cobalt-based alloys for extreme strength, low magnetic response and severe medical or oilfield duty rather than electrical conductivity.
Compare this family →Related Spring Products
These product pages include reference configurations from this material family. Review the geometry, then confirm the exact grade, dimensions and working loads during quotation.
- Variable-Diameter Compression Springs22 material-family reference configurations
- Straight-Leg Torsion Springs13 material-family reference configurations
- German-Hook Extension Springs11 material-family reference configurations
- Custom-Shaped Springs3 material-family reference configurations
- Tower-Shaped Compression Springs21 material-family reference configurations
- Conical Compression Springs16 material-family reference configurations
Related Material Engineering Guides
Compare material and dimensional reference data for the spring types used in your assembly.
- Beryllium Copper (QBe2) Compression Springs Reference DataMaterial and dimensional reference data
- Beryllium Copper (QBe2) Extension Springs Reference DataMaterial and dimensional reference data
- Beryllium Copper (QBe2) Torsion Springs Reference DataMaterial and dimensional reference data
- Beryllium Copper (QBe2) Spring Material Reference DataMaterial and dimensional reference data
- Phosphor Bronze (QSn4-0.3) Compression Springs Reference DataMaterial and dimensional reference data
- Phosphor Bronze (QSn4-0.3) Extension Springs Reference DataMaterial and dimensional reference data
RFQ Preparation
Information That Helps Us Select the Right Copper Alloy
Electrical spring parts need both mechanical and electrical requirements defined before the alloy and temper can be selected reliably.
- Part drawing and whether the component is wire, strip or stamped contact
- Required spring force and working deflection
- Target cycle life and mating/connection cycle count
- Current, voltage and allowable temperature rise if electrically active
- Maximum acceptable contact resistance if specified
- Required conductivity or magnetic-permeability limits
- Plating system, solderability or welding requirements
- Corrosive, marine, humidity or chemical exposure
- Required temper/hardness condition and bend direction for strip parts
- Any medical, aerospace or beryllium-processing compliance requirements
FAQ
Copper Alloy Spring Material Questions
Is phosphor bronze better than beryllium copper for spring contacts?
Neither is universally better. Phosphor bronze is cost-effective and easy to source for many connectors, while C17200 beryllium copper can provide much higher spring strength and fatigue margin when the added cost and processing requirements are justified.
What is the difference between C17200 and C17510?
C17200 is generally selected toward maximum strength, while C17510 is a high-conductivity copper-beryllium family with lower maximum strength but better current-carrying potential. The exact balance depends on product condition.
Can brass be used for a spring contact?
Yes for light-load and cost-sensitive parts, but brass is usually not the first choice for high fatigue, high contact force or long-term stress retention. Phosphor bronze or beryllium copper is often evaluated as duty increases.
Do copper alloy springs need plating?
Not always. Plating depends on the electrical interface, corrosion exposure, solderability, wear and appearance requirements. Tin, nickel, silver and other finishes serve different functions.
Are beryllium copper components safe to use?
Finished components are widely used. The main occupational concern is uncontrolled airborne beryllium-containing dust or fumes during certain manufacturing operations, so processing should be performed by suppliers with appropriate controls and compliance procedures.
Selection Logic
Specify the Electrical and Mechanical Function Together
Copper alloy selection should connect spring force, deflection and fatigue with current, contact resistance, plating, corrosion and magnetic requirements. Choosing only by conductivity or only by strength can produce the wrong contact system.
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