Copper Tungsten Class 10

RWMA Class 10 copper tungsten is a 45% copper / 55% tungsten refractory metal composite commonly used for flash and butt welding electrodes.

Class 10 copper tungsten’s ratio strikes a balance that most other electrode materials fail to replicate. It is genuinely heat-resistant, yet malleable enough for forming and machining, has high electrical and thermal conductivity, and has a low thermal expansion coefficient that keeps electrode geometry stable over long production runs. It’s the go-to whenever chromium copper starts to deform, and Class 11 is just a bit too much.

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Composition	Density	Hardness (min)	Electrical Conductivity	Thermal Conductivity
45% Cu / 55% W	0.448 lb/in³ (12.4 g/cm³)	Rockwell B 90	47% IACS	155 BTU/ft·h·°F (268 W/m·K)

Class 10 Copper Tungsten Composition and Manufacturing

The 45% copper / 55% tungsten split in Class 10 is intentional. Tungsten is the hardest naturally occurring metal and a true refractory metal, with a melting point above 6,100°F. The high tungsten content is what gives the material its wear resistance, arc resistance, and characteristically low thermal expansion.

Copper, in turn, is what keeps the material functional as an electrode, as it carries current, conducts heat away from the weld face, and provides the ductility that allows the composite to be formed and machined.

Class 10 copper tungsten composites are manufactured through a powder metallurgy process: a porous tungsten skeleton is pressed and sintered at elevated temperatures, and then liquid copper is infiltrated into the skeleton under controlled conditions. This combination produces dense, hard metals with a uniform microstructure, no binders, and zero to no porosity.

The result? A copper-tungsten alloy with the lot-to-lot consistency that is critical when qualifying material against an RWMA callout.

Class 10 Copper Tungsten Properties

The values below adhere to RWMA Bulletin 16 guidelines and are representative of commercially available Class 10 copper tungsten material, with a slight variance between specific lots and finished geometries. Lot-level certifications are available upon request.

Property	Imperial	Metric
Nominal composition	45% Cu / 55% W	—
Density	0.448 lb/in³	12.4 g/cm³
Hardness (minimum)	Rockwell B 90	—
Ultimate tensile strength	75 ksi	517 MPa
Electrical conductivity	47% IACS	—
Thermal conductivity	155 BTU/ft·h·°F	268 W/m·K
Coefficient of thermal expansion	5.0 µin/in·°F	9.0 µm/m·°C
Matrix melting point (Cu)	1,981°F	1,083°C
RWMA classification	Class 10	—

*Values are representative. Contact NSRW for certified material data or lot-specific documentation.

Applications of Class 10 Copper Tungsten Electrodes

Flash Welding Electrodes

Flash welding uses rapid arcing to heat the weld interface before the parts are forged together. The copper matrix maintains electrical and thermal conductivity where it needs to be, and its malleability helps welders form it into complex clamping geometries. Common applications include chain links, rebar splices, cutting tools, and ring welding for automotive and industrial parts.

Butt Welding Electrodes

Butt welding electrodes must maintain their geometry under sustained thermal and mechanical loads while delivering sufficient current to heat the workpiece interfaces consistently. On the other hand, Class 2 chromium copper works well for lower-resistance materials; however, on galvanized steel, terne plate, low-conductivity steels, or large-diameter wire, the environment becomes more challenging.

It’s also important to note that Class 10 copper tungsten’s high heat resistance and superior wear resistance keep electrode faces intact more consistently than copper-based alloys can withstand.

Other Applications

Class 10 is also regularly used in heavy-duty projection welding electrodes and projection welding inserts, where good electrical conductivity and high arc resistance under moderate pressure make it a practical choice. Seam welding bushings, electrode facings for resistance brazing, cross-wire welding, and light-duty stationary spot welding are among its other uses. For electrical contracts and heat sinks at high temperatures, it is comparable to other refractory metal composites.

How Class 10 Compares to Other RWMA Classes

Within the Copper Tungsten Family

RWMA classes 10–14 all cover copper-tungsten composites, with higher tungsten content as the class number increases. Class 10 sits at the high-conductivity end of that family. More tungsten means more hardness, wear resistance, and strength, and less tungsten means better electrical conductivity and easier machining. Here’s how they line up:

RWMA Class	Cu / W Ratio	Hardness (min)	Conductivity	Best Suited For
Class 10	45 / 55	Rockwell B 90	47% IACS	Flash & butt welding electrodes
Class 11	25 / 75	Rockwell B 98	44% IACS	Projection welding, light forging electrodes
Class 12	20 / 80	Rockwell C 28	40% IACS	Heavy projection welding, EDM electrodes
Class 13	0 / 100	Rockwell C 32	35% IACS	Severe projection welding, EDM, switch contacts
Class 14	0 / 100	Rockwell C 69	30% IACS	Stationary spot welding of nonferrous metals

Class 10 vs. Copper-Based RWMA Classes (Class 2 / Class 3)

RWMA Class 2 chromium copper and Class 3 beryllium copper both deliver higher electrical conductivity than Class 10, and for most standard resistance welding on mild steel or aluminum, they’re the right call. Your trade-off is going to be heat resistance, as copper-based alloys soften under thermal load faster than copper-tungsten composites.

You don’t have to worry about Class 10 holding its shape when the workpiece has high electrical resistance, electrode temperatures remain elevated during the weld cycle, or deformation from repeated cycling causes premature wear; Class 2 or 3, not so much. Class 4 beryllium copper is in the middle, but it doesn’t reach the arc or wear resistance of a true refractory metal composite.

Available Forms and Sizes

NSRW stocks class 10 copper tungsten in rod, bar, plate, and blanks. Rods are available from small diameters used for shaped electrode tips up through larger cross-sections for butt welding clamp blocks. Bar and plate stock are suitable for electrode facings, projection welding inserts, and seam welding bushings. Blanks can be cut to customer-specified lengths for drop-in placement on existing tooling.

Class 10 has a genuine machinability advantage over higher-tungsten grades like Class 13 and 14. The higher copper content allows standard carbide tooling to maintain tighter tolerances with less wear, making it practical for custom-machined electrodes with complex profiles.

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