[dtamburrino]

I purchased some ER70S-2 mild steel TIG welding rod and it has a copper coating on it. I have been told the copper coating will contaminate the weld. Does anyone know if all ER70S-2 has a copper coating on it?

[brian]

Yes it does have a copper coating on it but no it won't contaminate a finished weld bead. The coating is only to protect the filler from other contaminations and oxidation or rust, before use. What you have probably been told about is what is known as the fish eye, in your weld puddle. When you add filler to a weld puddle the very thin copper coating melts and floats to the top of the puddle but doesn't mix with the weld metal. One way to stop this is to sand the copper coating off right before using it. If welding multiple passes, I always wire wheel the solidified copper off of each pass.

[dtamburrino]

Thanks Brian, that answered my question.

[brian]

No problem.

[jtybt]

I found a couple rolls of copper coated mig wire when cleaning the shop. There's rust on the wire. Is there anything that can be done so it can be used or is it junk now?

[brian]

It depends on how much rust and how critical the pieces your welding are. It will work, but its hell on your liner and you will have some porosity. If you can, strip off enough to get to some cleaner wire.

[jtybt]

Thanks Brian.

[Rattletrap2]

Hello folks! I have a question regarding ER70S2 filler rod for tig. Actually, it is more to do with the rod diameter. I am using a 3/32" 2% Thoriated Tungsten on 1/8' steel. The rod diameter is also 3/32". It feels like it is a bit over powering for this application. Would 1/16" filler be better?
Thanks

[jpence38]

Not quite sure what you mean by overpowering. A 3/32 filler rod is acceptable for that work thickness. Maybe the problem lies elsewhere. i.e. Too low welding current maybe. Need more of a description to be for sure.


Jim

[Rattletrap2]

Jim,
Current was set at 90 amps. I guess this could be increased? even for a 3/32" Tungsten?

What I meant by "overpowering" was that it seems like a lot of filler for this joint. The joint in question was an edge joint.
Thanks

[jpence38]

I would try a current (amps) set at about 115-125. You are gonna get sufficient penetration when the two inside edges that are being welded are melted and fused on top of the filler that is added. I would say to go ahead and try using a 1/16 filler rod at 90-100 amps. As long as you have sufficient crown on the weld joint and it is not too flat you should be ok. By the way. Not trying to insult any one, but when you say edge joint are you making that description in accordance with an AWS "edge joint" or is that your description. The reason being is that they can be two very different joints. Just wondering.