Copper contamination in weld - spot test?

[InoxM]

Dear Forum
We're doing gas metal arc welding of structural steel parts with copper backing and fear that we get copper into the weld. I'm looking for a chemical spot test to find copper contamination in the welds. Does anybody know about such a test?
Any help is highly appreciated.
Michael

 

[racookpe1978]

We regularly use copper backing plates for turbine repair and refurbishing of the blade root keyways. The newly-deposited weld metal goes up against the copper.

I am not aware of any copper contamination of the repair area (weld built-up spots) that has ever caused problems either during later machining, NDE, or later operation.

 

[DVWE]

I wouldn't be too concerned about it. We use a copper backing on a mandrel for pressure vessels. The backing bar is formed so as to get a nice profile of the root, and is also fed 5 cfh of argon for backing gas. Welding process is also GMAW spray arc.

 

[hogan666]

If you have copper contamination it would most likely be evident by cracking. There are a wide variety of ceramic backing material on the market if this is a concern.

 

[MikeHalloran]

What's your welding wire plated with?



Mike Halloran
Pembroke Pines, FL, USA

 

[InoxM]

Dear all
Thanks for the help.
We're using a non-plated wire to prevent copper inclusions.
If I can't find an easy chemical test for copper contaminations (spectrometry is too expensive) we'll try the ceramic backings.

Michael

 

[Metalmeister]

The heat transfer through copper is so fast that the weld solidifies before the copper melts. Several % of copper is added to certain structural steels for corrosion resistance. It is present in solid solution in the steel and I'm not aware of any copper inclusion issue.

 

[gtaw]

Copper in small amounts can cause cracking problems. While some companies use copper backing, it is usually in conjunction with mechanized welding systems where the welding parameters can be controlled to prevent melting the copper backing or allowing the arc to impinge directly against the copper.

If you were to have a problem with copper contamination, it would most likely be evident by very small cracks in the contaminated area. A dye penetrant test or fluorescent wet magnetic particle test with an AC yoke will provide a positive means of locating cracks caused by the copper or other means.

You could also polish the area of concern and etch the weld (root). If copper is present, it will be obvious once the area is etched. AWS B2.1 can be used as a source of information of the types of etchants to be used with different metals.



Best regards - Al