ERCoCr-A TIG / GTAW filler metal is used for cobalt-chromium hardfacing overlays where wear resistance, heat resistance, and corrosion resistance matter. It is not a default filler choice. Before anyone loads rod into a torch, the job needs a verified WPS, base metal identification, service condition review, and confirmation that the filler classification matches the application.
This draft is written for welders, fabricators, and maintenance buyers who need a practical selection check. Treat the filler page as a starting point, not final approval. If the job is safety-critical or code-controlled, the manufacturer data sheet and governing procedure remain the authority.
Key Takeaways
- ERCoCr-A is a hardfacing filler used on cobalt-chromium overlay work, not a universal repair rod.
- Confirm the WPS, base material, and service environment before ordering or welding.
- Do not assume compatibility from classification alone; verify the substrate and overlay requirements.
- Check rod diameter, torch setup, and heat input control before striking an arc.
- Use the manufacturer data sheet and procedure documents for final acceptance criteria.
Selection Checks Before You Weld
Start with the base metal and the service condition. Hardfacing overlays fail when the filler is selected for the wrong wear mode or the wrong substrate. ERCoCr-A may be appropriate for wear and elevated-temperature service, but you still need to verify whether the job requires a different cobalt alloy, a nickel-based alloy, or a different hardfacing family.
Check: identify the part, its duty cycle, and the dominant damage mechanism. Is the issue abrasive wear, galling, impact, corrosion, heat checking, or a combination? If the wear mode is unknown, the selection is unknown (verify).
Inspect: look at the condition of the parent metal. Confirm whether the surface is cracked, work hardened, contaminated, or previously repaired. Previous overlays can change dilution and cracking behavior. If the history is unclear, treat the compatibility as unknown (verify).
Verify: compare the planned weld against the WPS and the manufacturer data sheet. The summary record for this filler indicates AWS A5.21 and ERCoCr-A classification, but process details, preheat, postweld practices, and any base metal limitations must be confirmed from the controlling documents.
Compatibility Checks on the Job
Compatibility is more than matching a filler name to a torch process. For TIG / GTAW hardfacing, the weldor needs a stable arc, clean surface preparation, and the correct rod diameter for the joint or overlay pass. The summary record lists 1/16 in, 3/32 in, and 1/8 in as common size references, but actual stock and fit for your job are unknown (verify).
Check: confirm the torch, cup, gas coverage, and stickout plan before starting. Poor shielding can create surface contamination, rough bead shape, or black specks. If the arc behavior is unstable, stop and inspect the setup before adding more filler.
Inspect: clean the work area thoroughly. Remove oil, paint, oxide, scale, and grinding residue. Hardfacing overlays are sensitive to contamination because defects can be buried under a sound-looking cap.
Verify: run a small test bead on a noncritical area or coupon if the procedure allows it. Check wetting, bead profile, and dilution expectations against the WPS. If the overlay shape or arc response looks wrong, do not proceed on production parts until the cause is identified.
Troubleshooting Support: If the Weld Does Not Look Right
If the weld starts cracking early, shows rough bead edges, or seems to wash too deeply into the base metal, stop and review the procedure. With hardfacing rod, the root problem is often not the rod itself but heat input, contamination, or an incorrect base metal assumption.
Check: confirm the polarity, shielding gas, and travel speed. If those settings are not documented, they are unknown (verify).
Inspect: evaluate bead shape, tie-in, and any signs of excessive dilution. A hardfacing overlay that mixes too deeply with the substrate may not deliver the intended wear properties.
Verify: re-check the substrate identification and service requirement. If the part is exposed to impact or cyclic thermal loading, the filler choice may need to change.
For tungsten-related setup problems, see TIG Tungsten Contamination Troubleshooting: Black Specks, Arc Wander, Dirty Starts, and Re-Grind Checks. For cup selection and stickout checks that affect shielding quality, see Square Wave 205 TIG Cup Size Selection Guide: Standard Cup, Gas Lens, and Stickout Checks.
WSP Filler Metal Finder Use
The filler metal finder page is useful as a starting point when you need to compare process and classification families. Use it to narrow down candidate filler metals, then confirm the WPS and manufacturer data sheet before release to the floor. It is not a substitute for application engineering or code review.
Check: use the finder to locate the process family and classification path that matches your job, then verify whether the part is a cobalt hardfacing overlay, a repair weld, or a build-up pass. Those are different decisions.
Inspect: compare the job requirements against the summary information available on the filler page. If the base metal, service temperature, or wear mechanism does not match, do not assume fit.
Verify: keep the controlling WPS and manufacturer documentation in the job packet. If there is a conflict between the summary page and the procedure, the procedure and manufacturer data control.
Filler metal finder: https://www.weldsupportparts.com/filler-metal-finder.html
Filler Metal Page Reference
The ERCoCr-A TIG / GTAW filler metal page identifies the product family as cobalt-chromium hardfacing filler for wear, heat, and corrosion-resistant overlays. Use that information to start the review, not to close it. Confirm the actual rod size, packing, and technical limits directly with the manufacturer data sheet and the job procedure.
Check: make sure the process is TIG / GTAW and the classification is ERCoCr-A before planning the job.
Inspect: confirm whether the part requires a hardfacing overlay or a different repair approach. If the repair objective is unclear, stop and clarify it.
Verify: review code requirements, if any, before welding. If code acceptance applies, the filler classification alone is not enough.
Filler metal page: ERCoCr-A TIG / GTAW Filler Metal
Safety Notes
- Use local exhaust ventilation and approved PPE for TIG hardfacing work.
- Assume grinding dust, oxide, and coatings may contain hazardous contaminants until verified otherwise.
- Do not weld on unidentified parts without confirming the base metal and service history.
- Follow shop procedures for hot work, shielding gas handling, and fume control.
- If cracking, spatter-like contamination, or abnormal arc behavior appears, stop and inspect before continuing.
FAQ
Is ERCoCr-A the right filler for every wear problem?
No. It is a hardfacing filler family, not a universal fix. Verify the wear mode, substrate, and service temperature before selecting it.
Can I rely on the filler metal page alone for procedure approval?
No. Use it as a selection starting point only. The WPS, governing code, and manufacturer data sheet control the final decision.
What if the base metal is unknown?
Treat the job as unknown (verify). Identify the part, confirm the substrate, and review whether the overlay is allowed on that material.
What should I inspect first when the arc looks unstable?
Check shielding, tungsten condition, cleanliness, and torch setup. Then verify gas coverage and stickout against the procedure.
Sources Checked
- ERCoCr-A TIG / GTAW Filler Metal
- WSP Filler Metal Finder
- TIG Tungsten Contamination Troubleshooting: Black Specks, Arc Wander, Dirty Starts, and Re-Grind Checks
- Square Wave 205 TIG Cup Size Selection Guide: Standard Cup, Gas Lens, and Stickout Checks
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