C18200 Class 2 Chromium Copper (RWMA Class 2)

C18200 chromium copper is an RWMA Class 2 copper alloy used for resistance welding electrodes and other high-heat, high-current components, and contains approximately 1% chromium with copper making up the remainder. C18200 combines about 80% IACS conductivity with greater strength, hardness, wear resistance, and resistance to softening at elevated temperatures.

What Is C18200 Chromium Copper?

C18200 contains approximately 0.6–1.2% chromium, with copper making up the balance. The chromium strengthens the alloy through precipitation hardening: During heat treatment, chromium-rich precipitates form within the copper matrix, increasing hardness and strength without sacrificing as much conductivity as a higher-strength alloy would. 

That balance is what makes C18200 an RWMA Class 2 alloy, as it sits between the higher-conductivity, lower-strength Class 1 alloys and the higher-strength, lower-conductivity Class 3 alloys. For resistance welding, C18200 provides a practical combination of conductivity, strength, and resistance to wear and softening. 

C18200 may appear on specifications as C182, CDA 182, alloy 182, UNS C18200, or CuCr. Trade names for equivalent or closely comparable Class 2 chromium copper materials include Mallory 100, Tuffaloy 77, and Ampcoloy 97.

As a heat-treatable alloy, its properties can be tailored through the appropriate processing to meet the demands of the application.

C18200 Chromium Copper Properties

C18200’s properties vary with form, size, temper, and heat treatment, so the figures below should be treated as typical material-level values rather than guaranteed properties for every stock size. The tables that follow provide the more specific mechanical properties by form and size.

Property	Value
UNS number	C18200
RWMA classification	Class 2 (Group A)
Common designations	C182, CDA 182, alloy 182, CuCr
Nominal composition	0.6–1.2% Cr, balance Cu (Cu + named elements 99.5% min)
Density	0.321 lb/in³ (8.89 g/cm³) at 68°F
Electrical conductivity	80% IACS at 68°F, typical
Thermal conductivity	187 Btu/ft·hr·°F at 68°F
Hardness	65–75 HRB, size and temper dependent
Tensile strength	51–72 ksi, precipitation hardened
Yield strength	36–77 ksi, temper dependent
Modulus of elasticity	17,000 ksi
Coefficient of thermal expansion	9.8 × 10⁻⁶ per °F (68–212°F)
Melting point	1,967°F liquidus / 1,958°F solidus
Resistance to softening	stable to approximately 700°F
Machinability rating	20 (free-cutting brass = 100)

Key Properties of C18200 Class 2 Copper

Minimum Physical Properties

• Diameter – Round Stock (Cold Worked)

  Size Range in MM	Size Range in MM	Hardness Rockwell	Conductivity % I.A.C.S.	Yield Strength KSI (typical)	Ultimate Tensile Strength (typical)	Elongation % *(typical)
  Up to 1″	Up to 22	75 HRB	75%	55	65	13%
  Over 1″ to 2″	Over 25 to 51	70 HRB	75%	55	59	13%
  Over 2″ to 3″	Over 51 to 76	65 HRB	75%	55	55	13%

• Thickness – Square, Rectangle, and Hexagonal Bar Stock (Cold Worked)

  Size Range in MM	Size Range in MM	Hardness Rockwell	Conductivity % I.A.C.S.	Yield Strength KSI (typical)	Ultimate Tensile Strength (typical)	Elongation % *(typical)
  Up to 1″	Up to 25	70 HRB	75%	45	65	13%
  Over 1″	Over 25	65 HRB	75%	40	55	13%

• Thickness – Forgings

  Size Range in MM	Size Range in MM	Hardness Rockwell	Conductivity % I.A.C.S.	Yield Strength KSI (typical)	Ultimate Tensile Strength (typical)	Elongation % *(typical)
  Up to 1″	Up to 25	65 HRB	75%	45	55	13%
  Over 1″ to 2″	Over 25 to 51	65 HRB	75%	45	55	13%
  Over 2″	Over 51	65 HRB	75%	40	55	13%

• Chemical Composition

  Cu	Cr	Fe	Pb	Si
  Rem.	.6-1.2	.10 max	.05 max	.10

RWMA Class 2 Requirements & How C18200 Meets Them

RWMA Class 2 is a specification, not a single alloy. The Resistance Welder Manufacturers Association (RWMA) classification system groups alloys according to properties important to resistance welding, including electrical conductivity and hardness. Class 2 alloys are designed to provide a useful balance of conductivity, strength, hardness, and resistance to softening.

The published Class 2 minimums are approximately 75% IACS electrical conductivity and 65 HRB hardness. C18200 meets those minimums and is one of the most commonly used alloys in the class. C18150 chromium-zirconium copper is another Class 2 alloy.

You may see C18200 listed at 75% IACS in minimum-property tables and around 80% IACS as a typical material value. Those numbers aren’t necessarily contradictory, as 75% represented the Class 2 minimum shown for applicable forms, while 80% is the typical conductivity value for C18200.

Here’s the practical takeaway: C18200 gives you more strength and heat resistance than a high-conductivity Class 1 alloy while retaining more conductivity than any Class 3 options. If you’re comparing materials for a resistance welding application, explore NSRW’s copper alloys to see how the classes differ. 

Applications

C18200 is primarily used where a component needs to carry electrical current while withstanding repeated heat, pressure, and wear. Its combination of conductivity, hardness, and resistance to softening makes it particularly well-suited to resistance welding equipment and high-wear industrial tooling.

Resistance Welding Electrodes and Dies

C18200 is widely used for spot and seam welding electrodes, backup electrodes, flash and butt welding dies, and beam welding wheels. It maintains its shape and useful conductivity through repeated weld cycles, while its hardness and resistance to softening help extend component life under heat and mechanical pressure.

It is especially useful for welding cold-and hot-rolled steel, stainless steel, galvanized steel, and lower-conductivity brasses and bronzes. For production welding, that combination of conductivity and durability makes it a practical choice when electrodes or dies need to withstand repeated thermal cycling without deforming too soon.

Electrode Holders, Adaptors, and Fixtures

C18200 is also used for electrode holders, jaws, adaptors, welding arms, shanks, platens, and other current-carrying structure components. These parts need enough conductivity to transfer welding current efficiently, but they also have to withstand mechanical pressure and repeated exposure to heat.

For automated and high-production welding systems, C18200’s strength and resistance to softening can help components maintain their geometry and provide consistent current transfer over long service periods.

Industrial and Tooling Applications

Outside of resistance welding, C18200 is used for circuit-breaker components, heat sinks, cable connectors, wear plates, plastic molds, and high-wear tooling. Its conductivity makes it useful in applications where heat or current is required to move with more efficiency. Along with that, its hardness and wear resistance provide durability in demanding service environments. 

It can also be used for tooling components like inserts, dies, and clamps that go through repeated impact, friction, or thermal stress. When frequent component replacement can interrupt production or affect dimensional accuracy, C18200’s resistance to wear and softening can make it a practical material choice. 

C18200 vs. Other RWMA Classes and Alloys

Choosing an RWMA copper alloy involves more than simply picking the highest strength or highest conductivity, as the right material depends on the kind of environment or conditions your electrode or component will experience: electrical load, heat, mechanical force, wear, sticking, or some combination of them all.

C18200 vs. C18150 Copper Chromium Zirconium

C18200 and C18150 are both RWMA Class 2 copper alloys used in demanding resistance welding applications. C18150 adds zirconium to the copper-chromium system, which can improve creep resistance and help reduce electrode sticking, particularly when welding galvanized steel or running demanding production cycles.

C18200 is the more general-purpose option as it offers a strong combination of conductivity, hardness, and heat resistance, and is more readily available. C18150 can be a better fit when you’re having to deal with electrode sticking, extended high-temperature exposure, or high duty cycles; otherwise, C18200 is a strong Class 2 starting point. NSRW stocks C18150 Class 2 chromium-zirconium copper in bars, rods, rounds, electrodes, and custom shapes.

Class 2 vs. Class 1 & Class 3

Think of the RWMA classes as a selection ladder, not a ranking.

• Class 1: Higher conductivity and lower strength; a good fit for highly conductive applications and certain coated materials.
• Class 2: The general-purpose balance of conductivity, strength, hardness, and heat resistance.
• Class 3: Higher strength and lower conductivity; better suited to heavier sections, higher electrode forces, and applications where mechanical durability takes priority.

For many standard resistance welding applications, Class 2 is the middle ground that makes the most sense. If you need a welding component that can handle substantially greater mechanical or thermal demands, a Class 3 alloy may be worth the conductivity trade-off.

If you’re selecting a complete resistance welding electrode, NSRW can help match the electrode material and design to your welding application.

C18200 vs. Trade-Name Equivalents

Mallory 100, Tuffaloy 77, and Ampcoloy 97 are trade names associated with Class 2 chromium copper materials comparable to C18200. NSRW can help identify the appropriate material and provide a quote for any print that specifies trade-name equivalents. 

Available Forms and Sizes

NSRW stocks C18200 chromium copper in forms that resistance welding and industrial buyers actually need, including round, squares, hexagons, rectangles, plate, and custom shapes. C18200 plate and C18200 sheet applications can also be supported when flat stock is the right fit for the job.

And if you’re looking for a particular length or geometry, NSRW offers cut-to-length material, custom shapes, and machine electrode tips. Don’t settle for forcing your application to work with whatever material you can find; our goal is to get you the material that works best for your job.

Whether you’re sourcing chromium copper rod for an electrode, plate for a fabricated component, or a custom-machined welding part, NSRW can help determine the appropriate form and specification.se and inventory to meet your needs.

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Why Choose NSRW for C18200 Chromium Copper

Here at NSRW, we bring something to C18200 sourcing that a general metal distributor can’t: a mastery of resistance welding. Get the right material for your application with our combination of inventory and expertise. 

• In stock C18200: Available in bars, rods, plate, and other forms for a range of jobs
• Custom fabrication: Cut-to-length and custom-shaped C18200, including machined electrode components
• Resistance welding expertise: Technical support from a team familiar with RWMA copper alloys and resistance welding applications, and can make recommendations on Class 2 and Class 3
• Reliable supply: Extensive inventory and fast quote turnaround to help keep your project moving

Whether you need C18200 for resistance welding electrodes, tooling, or another current-carrying component, we would be glad to help you select and source the material for the job.

Frequently Asked Questions

• What is RWMA Class 2 copper?

  RWMA Class 2 copper is a category of copper alloys designed to balance electrical conductivity with strength, hardness, wear resistance, and resistance to softening. C18200 chromium copper is one of the most commonly used Class 2 alloys.

• What is C18200 chromium copper used for?

  C18200 is commonly used for resistance welding electrodes, seam welding wheels, projection welding dies, flash and butt welding dies, electrode holders, welding arms, current-carrying structural members, and other high-heat, high-current components. It is also used in applications such as heat sinks, cable connectors, circuit-breaker components, and wear-resistant tooling.

• What is the difference between C18200 and C18150?

  Both C18200 and C18150 are RWMA Class 2 copper alloys. The difference between them is that C18150 contains chromium and zirconium, providing improved creep resistance and reduced electrode sticking, making it a strong choice for high-duty-cycle welding and galvanized steel. C18200, on the other hand, is a versatile, general-purpose Class 2 alloy with broad availability.

• What is the difference between RWMA Class 2 and Class 3 copper?

  Class 2 copper alloys offer a balance of conductivity, strength, and heat resistance, while Class 3 offers higher strength and durability at the expense of electrical conductivity.

• What is the conductivity of C18200 chromium copper?

  C18200 has a typical electrical conductivity of approximately 80% IACS at 68°F. Applicable minimum-property tables may specify 75% IACS, depending on the material form and condition.

• Can C18200 chromium copper be heat-treated?

  Yes, C18200 chromium copper can be heat-treated because it is a precipitation-hardening copper alloy, meaning its mechanical properties can be enhanced through appropriate heat treatment.

• What is C18200 equivalent to?

  C18200 is equivalent to C182, CDA 182, alloy 182, UNS C18200, CuCr, chromium copper, and chrome copper. Trade names associated with comparable Class 2 chromium copper include Mallory 100, Tuffaloy 77, and Ampcoloy 97.

• How hard is C18200 chromium copper?

  C18200 usually falls in the 65–75 HRB range, depending on size, form, temper, and processing.

Shop C18200 Chromium Copper

Looking to buy C18200 copper chromium material or related high-strength copper alloy components? Our team can guide you through material selection, fabrication options, and pricing, whether you’re fabricating electrodes, dies, holders, structural components, or other high-current applications. Contact NSRW today to speak with an expert about your needs or start ordering now.

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