GMAW of Galvanealed Steel

By Lawrence (*****)

Date 02-27-2014 21:39 Edited 02-27-2014 21:42

I've done some D1.3 PQR's in the last year on Galvanized and Painted gage steel.

Our Galv was G90 (0.75 mils per side)

My trials convinced me that GMAWP (adaptive feedback pulse processes) don't like coatings at all.

I got the best results (less spatter) with parameters in the globular range/no pulse and 88/12 gas (90\10 is darned close though)

Between 19-22 volts and 160-200 Amps allowed us to do thicknesses between 16ga and 12ga.

I preferred the absolute low end on both current and voltage for the 16ga ... But could have gone higher than our max for the 1/8"

Whipping *may* burn off some galvanized, but it also increases spatter. Either technique can be made to pass the destructive testing, it's a matter of what you want to see.

The Amps/WFS can vary greatly here dependant on CTWD (Contact Tip to Work Distance) and also how far the contact tip is recessed into the nozzel (a thing operators do to avoid spatter fracking out the tips) So you may find that the WFS can be much higher than you suspect to get a current value you are shooting for.....(this can be a good thing for deposition rates if you are making widgets)

Again... I considered Pulsed GMAW a total failure on Galvanized... The arc disturbance with the zinc burn-off (in my opinion) really messes with the Advanced Synergic feedback that Access offers on GMAWP with thin material. Not Millers's fault <this time> Just how it works.

Edit:

Do it every day... Hate it every day.... NOBODY can like GMAW on Galv.

By Milton Gravitt (***)

Date 03-03-2014 13:31

Lawrence, I hope I never work where they have that many galvanized widgets to weld, but if I do I think I would follow Walt's advice.

M.G.

By Lawrence (*****)

Date 03-03-2014 15:38

This is the second post that seems to infer that I am somehow suggesting that Sperko's advice is something other than 100% correct.

What did I say that makes you think that?

By Milton Gravitt (***)

Date 03-03-2014 18:21

Lawrence, I think you took my post the wrong way,it's right the opposite.

M.G.

By Lawrence (*****)

Date 03-03-2014 19:28

Oh... Alrighty then :)

Smokey mess... But doable

By PlasmaHead2 (***)

Date 02-27-2014 22:50

I believe that we need a time machine to go back and hit the first welder/boss/manager who thought it was a good idea to weld over galvanized with a brick. In the head... A few times so that this silly idea never started.
We made a bunch of duct work from 16 ga galvanized sheet. Most were at least 4 feet tall with some as big as 6ft, bent to from a 3 sided box with sheets welded on to seal it up. Lots of open corners and a few tiny fillets on some .25 thick flanges. I admit, this was a codeless venture so no testing of properties was ever done or let alone thought about.... :red:

But for what it was it serves its function well and without complaint, except from me when they bring more to weld up....
The best setup we came up with at work for welding up duct from 16 gauge was with .023 70-s6 and a 90He 7.5Ar 2.5CO2 mix blend. Its been a while and I don't remember exact settings, but im thinking about 15 to 16 volts and maybe 250 to 350 IPM wire feed? I pushed with very little to no side to side or back forth motion, or as much as the fit-up allowed. Might not work so well for a groove... maybe with motion? I did grind the galvi back from the seams but no more than .25 inch and usually not from the insides.
The He trimix ran with much less spatter and didnt burn off the galvanised as bad as say 75ar 25 co2. No idea why, but it works and it saved my arm lots of spatter burns. the .023 wire was so we didnt have to blend off a huge lumpy welds.

By TimGary (****)

Date 02-28-2014 18:24

"I believe that we need a time machine to go back and hit the first welder/boss/manager who thought it was a good idea to weld over galvanized with a brick. In the head... A few times so that this silly idea never started."

Amen Brother...

By Metarinka (****)

Date 03-06-2014 20:37

Why wouldn't you knock off the galvanizing with a wire wheel or flapper disk prior to weldidng. I won't weld over galvanizing due to the health risks. No point in ruining a guys lungs to save a little time or money or to buy the right thing.

By PlasmaHead2 (***)

Date 03-06-2014 22:50

I do for the most part... Sometimes they were fitted and tacked and then given to me to weld... without pre-cleaning. I'd grind off what I could without having to break everything apart.
The guys who usually do the bending work never like to take a grinder to the flat parts... when it would be easy... and the last few times I would have gone and done it my self if not for being on a different job.
Fans and Respirators were in use.

By welderbrent (*****)

Date 02-28-2014 00:07

Interesting and good comments by Lawrence and Clif.

For myself, I always thought I had better success with NR 211 or an equivalent. Forget something with gases and nozzles.

Now, regardless of which one you choose, watch anything done in the vertical closely. Many guys can make it look good but don't get the penetration required to actually be welded. They pass the test then change everything in the actual production and it doesn't work. More than once I have knocked on them with a hammer and had them separate with no penetration showing through the zinc.

Just my two tin pennies worth.

Have a Great Day, Brent

By 46.00

Date 02-28-2014 07:45

What about the health and safety issues?

http://www.keytometals.com/page.aspx?ID=CheckArticle&site=kts&NM=191

But in answer to your question, here is an articule from the great man himself, Walt Specko:

http://www.sperkoengineering.com/html/articles/WeldingGalvanized.pdf

By welderbrent (*****)

Date 02-28-2014 09:15

It should not be a surprise that Walt's article is very well done and informative about the question at hand.

Thanks for sharing 46.00.

Have a Great Day, Brent

By Milton Gravitt (***)

Date 02-28-2014 12:30

This here is what tells me something (The zinc at and near any welds is actually burned off by the heat of the arc, removing the protective zinc coating.) now if this is the case why can't you clean or grind the part before you weld it.

M.G.

By Lawrence (*****)

Date 02-28-2014 12:45 Edited 02-28-2014 13:10

Milt

Of course you can grind it off !

But it takes time and resources.

It really depends quite a bit on what you are doing.

The OP mentioned Fillets and Flare Bevels on Gage material, flat and horizontal... And this is exactly what my PQR's were run on so I thought to chime in. :) (we also qualified grooves in the same range)

Those joint combos typically tend toward large production runs... And nobody wants to take the time to do surface prep on 50,000 widgets.

The grinding produces particulate of it's own and PPE requirements are not that different from welding.

Also also, D1.3 PQR requirments are much less rigorous than D1.1 ... Things like porosity are not even mentioned in the inspection criteria :)

If I'm doing 1 off work.... The zinc comes off... Or if I'm really smart I don't deal with Galv at all.

If it's D1.1 work? I would use all my persuasive efforts to avoid trying to qualify a procedure with a coating.... Just because the PQR can be done does not really always translate to operators making welds equal to PQR quality done in a lab or controlled environment.

D1.3 ? Well it asks less of the welds (fact) And we do spotchecks, breaks and macros on coated materials.... And the process works in production on coated materials.... Does it spatter? Yes.. Do the welders want to move to the structural areas so they can work on uncoated steel? Oh yes!

Edit:

Walt Sperko also mentioned the issue of the increased likelyhood of hot cracking with high silicon fillers like ER70S-6 GMAW wire, and Suggests a lower S-3 type of filler. It's hard to disagree with walt.

I walked into a situation where S-6 had been used for years and we ran the PQR's with -6 as well.. I don't think in the D1.3 world that the change from S-6 to S-3 would require requalification... (See table 4.2)

By js55

Date 02-28-2014 13:20

Lawrence,
If you are going to disagree with Walt, pick your battles and do your homework. Because he has. It astonishing what he carries around in his head. Great guy.

By Lawrence (*****)

Date 02-28-2014 13:51 Edited 02-28-2014 13:59

Reread:

I sit at Walt Sperko's feet and listen. I think of him as a personal mentor.

Walt is absolutly right about filler metal selection.

I only mentioned that our procedures passed destructive testing using the "less optimal" filler. :)

I mentioned this because the original post indicated the less favorable ER70S-6 filler and NOBODY else had brought up the subject.

Also brought the point that changing filler to the more desirable S-3 I believe to be allowable in the scope of D1.3

If the OP is qualifying procedures now... It might not be too late to make a change.

Edit:
Was trying to be helpful and offer the best solution when it comes time for production.
I guess I need to learn how to write better :)
.

By jwright650 (*****)

Date 02-28-2014 14:11

Re: GMAW or FCAW on galavanized materials
I have yet to have satisfactory results without removing the coating with any of these machine wire fed processes.

SMAW seems to deal better with dirty or galvanized joints.

By Lawrence (*****)

Date 02-28-2014 14:21

SMAW on 16 ga. ?!?!?!

By jwright650 (*****)

Date 02-28-2014 14:26

Just commenting on the processes that I have seen successful in dealing with Galvanized materials.

By kcd616

Date 03-02-2014 14:19

Lawrence
1/16 e6013
done it a time or two
and as low as 24 ga.
hope this helps
sincerely,
Kent

By TimGary (****)

Date 02-28-2014 15:10

Thanks for everyone's responses. Great information!
I'm in the early phases of testing now, trying to figure out the best variables before running PQRs.
I like the idea of deliberately making joint gaps to allow the gases to escape. A lot of the gross spatter that I was seeing is a result from gases building up under the molten puddle to the point that the whole puddle would blow out periodically.
We typically use ER70S-3 wire, but I chose S-6 for testing thinking the extra deoxidizers would be helpful. Silly me...
I'm very concerned about delayed cracking due to zinc embrittlement as our welds must have structural integrity.
I'm working to the AWS D14.3 Spec.
Has anyone tried the Hobart Fab Core F-6 wire?

I greatly appreciate the sharing of info on this and will do the same as my testing continues later next month.

Tim Gary

By Cumminsguy71 (*****)

Date 03-01-2014 11:50

I wait to see and hear about the results Tim!

I did a job with a friend a few years back, no grinding but welding a structure that was all galvanized. Spent three weeks on that job I think welding over that stuff. Definitely a different motion, tricks to doing it with SMAW. Have never tried it with GMAW but interested in hearing your results.

Shawn

By 46.00

Date 02-28-2014 22:41

thanks! this is to Brents reply.