ERNiCu-7 and ERNiCrMo-4 are both nickel-alloy TIG filler classifications under AWS A5.14, but they belong to very different alloy-selection paths. ERNiCu-7 is a nickel-copper filler commonly associated with Monel-type nickel-copper base materials. ERNiCrMo-4 is a nickel-chromium-molybdenum filler associated with C-276 / UNS N10276 and severe corrosion-service applications. They should not be treated as interchangeable just because both are nickel-alloy rods.
The fast distinction
| Selection question | ERNiCu-7 | ERNiCrMo-4 |
|---|---|---|
| AWS family | A5.14 | A5.14 |
| General alloy path | Nickel-copper / Monel-type materials | Nickel-chromium-molybdenum / C-276-type materials |
| Manufacturer example | ESAB OK Tigrod NiCu-7 | ESAB Exaton NiCrMo-4 GTAW |
| Typical decision driver | Base-alloy identity and nickel-copper service | Base-alloy identity and aggressive corrosion service |
| What the classification alone does not prove | That it fits every Monel or dissimilar joint | That it fits every corrosive-service or dissimilar joint |
What ERNiCu-7 is designed around
ESAB’s OK Tigrod NiCu-7 is classified to SFA/AWS A5.14 ERNiCu-7. ESAB describes it as a bare nickel-based rod alloyed with about 30% copper for welding base materials of the same type, and says it can also be used to join those nickel-copper alloys to steel. ESAB also describes resistance characteristics for flowing seawater and several chemical environments. Those statements are product-specific manufacturer guidance, not a blanket approval for every marine, chemical, or dissimilar-metal joint.
The practical takeaway is that ERNiCu-7 starts with a nickel-copper base-metal question. If the job involves a Monel-type alloy, identify the exact base-metal grade and then check the WPS, governing code, service conditions, and filler manufacturer’s data. The fact that a rod is ERNiCu-7 does not establish diameter, package form, shielding requirements, current range, or procedure acceptance for a specific job.
What ERNiCrMo-4 is designed around
ESAB’s Exaton NiCrMo-4 GTAW product is classified to SFA/AWS A5.14 ERNiCrMo-4. ESAB identifies it as a low-carbon nickel-chromium-molybdenum alloy of the C-276 family and lists joining of UNS N10276 and other nickel-chromium-molybdenum alloys among its uses. The manufacturer also describes applications in chemical processing, pollution control, pulp and paper, waste treatment, sour-gas service, and other aggressive environments.
That application list is useful for understanding why ERNiCrMo-4 exists, but it does not make the filler universal. Corrosion performance depends on the complete weld-metal chemistry, dilution, base materials, service media, temperature, fabrication condition, and procedure. ESAB also notes that another alloy can be preferred in certain oxidizing chloride-containing environments. That is exactly why “corrosion resistant” is not enough information for filler selection.
Why these two classifications are easy to confuse in a search
Online catalogs often group nickel-alloy TIG rods together. A buyer may see AWS A5.14, nickel filler, similar rod diameters, and a list of corrosion-related applications and assume the products are neighboring substitutes. They are not. The alloy systems are different: nickel-copper versus nickel-chromium-molybdenum. The right starting point is the documented base-metal grade and service requirement, not the fact that both rods sit in the same nickel-alloy catalog section.
Use WSP pages as lookup starting points
- WSP ERNiCu-7 TIG filler page — nickel-copper / Monel-type starting point.
- WSP ERNiCrMo-4 TIG filler page — C-276 / nickel-chromium-molybdenum starting point.
- WSP Filler Metal Finder — narrow the candidate classification when the grade is not already known.
- WSP Alloy Support / AWS lookup library — compare nearby classifications and process pages.
These WSP pages are lookup aids, not approved welding procedures. They preserve the classification and common alloy path so a buyer or welder can ask the next correct question. Final selection still belongs to the applicable WPS, code or specification, engineering requirements where applicable, exact base-metal identification, service conditions, and the current manufacturer data sheet.
Verification checklist before ordering either filler
- Identify every base metal by documented grade, not color, magnet response, or a generic “nickel alloy” description.
- Determine whether the weld is matching, dissimilar joining, overlay, cladding, repair, or another qualified application.
- Confirm the AWS classification required by the WPS or engineering documentation.
- Verify the exact filler product form, diameter, package size, manufacturer, and lot requirements.
- Review corrosion medium, service temperature, dilution, heat treatment, and other service-specific requirements.
- Use manufacturer “typical” chemistry or mechanical data as product information, not as a substitute for AWS specification limits.
Bottom line
If the job is built around a nickel-copper / Monel-type alloy path, ERNiCu-7 is the classification to investigate. If the job is built around C-276 or a nickel-chromium-molybdenum corrosion-service path, ERNiCrMo-4 is the classification to investigate. That is a starting distinction, not a final procedure. The safest and fastest ordering workflow is to identify the base metal and service first, then confirm the exact classification and product against the governing WPS and manufacturer documentation.
Manufacturer sources
Featured image pending. No generic rod photo was attached because it could imply a specific product or package that was not independently verified for this comparison.
Leave a Reply