Surfacing Welds

By Stephan (***)

Date 02-25-2008 20:03

Jeff,

this is an extraordinary good post!

You won't believe it, but I am currently preparing a paper for the next Annual IIW-Assembly's International Conference being held in Graz Austria this year.

The conference is headlined with:

"Safety and Reliability of Welded Components in Energy and Processing Industry"

The paper treats the "Overlay Welding" which I have alternatively or specifically termed "Cladding" (being used furthermore within the paper) of particular heat affected components.

It deals with the usage of sophisticated (controlled) GMA-Welding in combination with NiCrMoNb-fillers (ALLOY 625 and above) for achieving an improvement of corrosion- and erosion resistance conditions both on-site and in the shop.

To be honest, before I have started to busy myself with this special field of applications (surfacing) I would have never guessed that it could be that interesting. But I must admit: "Huuuh, it is... extremely!"

Your post is thus a godsend!

By my research I have - amongst others - found out as well, that there is likely no other nation in the world, having collected so much experience in "Surface-layer welding" over the course of the decades, as the United States of America. I have been told by a German expert that the USA is leading in the wide field of different applications. By pursuing the AWS Welding Journal articles and much more, I guess that I can fully agree with this statement.

The more I was astonished by having read your post. I was 100% convinced that every little detail in regard to this particular field of welding has been clarified in the USA (even by knowing the importance of this great and continuously growing sector for the welding industry) and would have been thus out of any discussion.

However, as you can see, in these few previous sentences I have used alone 4 different terms:

1. Overlay Welding
2. Cladding
3. Surfacing
4. Surface-layer welding

and I have read a lot more in the recent past.

By the way, in Germany we're generally using the term "Cladding" for even these special "ALLOY 625" applications.

But I know as well the German term "Plattieren" which deals with even this "... process of providing a solid corrosion resistant plate (or tube) material to a less corrosion reistant plate or pipe substrate...". The translation of even this term and product respectively, is - astonishingly - "Cladded Steel" and the welding procedure for those components is headlined with "Welding of Cladded Steels". Hmm, very strange.

So I beg your understanding that I will devotionally follow this discussion initiated by you. Not alone since it is interesting at all by having dropped a very interesting new aspect for me, but as well a bit self-interested (:-)) since hereby I do humble hope to find a clarification of what correct terms I can use now and in the future.

Best to you,
Stephan

By js55

Date 02-25-2008 20:41

Stephen,
I took a job a while back with a premier 'overlay' company. Both hardfacing and corrosion resistant. The overlay/cladding dual terminology seemed to be an industry standard in all my communications. Especially with subs who were supplying us with clad pipe and plate. And since this was my first comprehensive foray into cladding/overlay.
But, to make matters worse. Strip applications revert back to the cladding terminology.
So, if its a base metal 'stuck' (like Hipping) to a base metal its cladding, if its ESW/SAW Strip its cladding. If its SAW, GMAW, FCAW, GTAW, wire etc., it seems to be overlay, except by AWS standard in which case it would be cladding as well.
I just think the corrosion people will be a little more reluctant to climb on board with the AWS terminlogy since it will be confusing unless the BM/BM applications receive another name. The hardfacing guys should have little problem. At least not the high carbon FeC type hardfacing guys anyhow. There isn't to my knowledge any FeC cladding (BM/BM) going on since the FeC's need a substrate to even exist.

By Stephan (***)

Date 02-25-2008 22:01 Edited 02-25-2008 22:11

Jeff,

thank you, good points!

I guess I know what you mean.

Under consideration that I have no detailed knowledge of the AWS standard you are speaking about (I apologize) I guess that even this standard is the basis for us in Europe or Germany respectively, to use the term "Cladding" for each application of "surface-layer" or "overlay" welding, being different to all those applications falling explixcitly among the regime of the appreciated "hardfacing guys".

Since this latter particluar field in "surfacing" is even particularly named "hardfacing".

I personally interprete this as the try to express that the "cladding" operation is mainly performed for improving the resistance of the base metal against chemical a/o thermal influences*, whereas hardfacing is carried out to increase the resistivity mainly against abrasion or wear.

In case of cladding again it does not matter how the "clad-" or "surface"-layer is deposited upon the base metal, or better, which welding process has been used for accomplishing this. As I have found out, "Cladding" is carried out by using a wide spread assortment of fillers (solid- as [exceptional] flux cored wires as well as strips) and a row of "Submerged- and Open-Arc" processes.

I personally would mean that - comparable to "Fusion Welding" - a generic term as "Overlay Welding" could clarify the "confusion".

Similar to Fusion Welding one could then for instance separate the different subgroups as "cladding", "hardfacing",...

But I might be wrong by thinking so and this would not resolve the issue.

I'm curious what the other experts beside you may post on this interesting topic.

Best,
Stephan

* Edit: Of course in many applications one can have as well very complex combinations or interactions between the different impacts (corrosive + thermal + wear). Just forgotten... :-)

By Stephan (***)

Date 02-26-2008 08:18

Oh dear Jeff!

I hope I haven't stifled this interesting topic before it could do its first breath!

Best,
Stephan

By js55

Date 02-26-2008 14:27

Stephen,
I don't think so. There's probably just not that many overlay/cladding/surfacing guys wishing to step into this one I suppose.

By jon20013 (*****)

Date 02-26-2008 15:52

Ummmm... yep. I have to admit js55, I tend to like the examples provided by yourself and Stephan much more than the current definitions. Perhaps I'm being a bit too simplistic but I also tend to think of cladding more akin to a "plating" operation if you will, like an explosively bonded material rather than a "surfacing treatment" and I include the SAW and ESW processes in that "surfacing" treatment. Just two cents from one who probably shouldn't be trying to define things! ;-) Have done loads and loads and loads of hardfacing, to me that remains a surface conditioning... or surfacing, if you will. Might even take it one step further and mention that B&PV discusses clad vessels, meaning multi-layers...

By js55

Date 02-26-2008 16:15

Explosion bonding!! Thank you. I was trying to think of that and my mind went blank, and I was too lazy to look it up. Is explosion bonding, hipping, AND strip welding all cladding?

By CWI555

Date 02-27-2008 00:30 Edited 02-27-2008 00:34

Maybe this is taking it a bit far but....
The etymology of the word clad is:

clad
1300ad Old english claepan to cloth
later effectively redefined around 1852 When it was first used in conjunction with metal.. Iron+clad as in the noun iron clad ship.

1300 again
over + lay also in 1175 overlie, merging sometime in the 1800's. used as a noun to mean as in printing, later as in transparent sheet over documents around 1938
websters defines the noun as a covering either permanent or temporary: as a: an ornamental veneer b: a decorative and contrasting design or article placed on top of a plain one c: a transparent sheet containing graphic matter to be superimposed on another sheet
The transitive verb as 1 a: to lay or spread over or across : superimpose b: to prepare an overlay for

Given that clad was to cloth or in the case of a ship protection from mechanical or thermal damage depending on how you look at it, I believe the word should apply to any surface conditioning in which added strength or toughness is required such as found in hydro Dam pen stock claddings.

Overlaying should apply to applications in which one material is protected by another from external factors such as contamination, corrosion etc due to it's etymology being originally meant for putting a transparent sheet over say a sailing map to protect it from damage from the sea, or other such application.

That would be my two cents worth,
Gerald

By Stephan (***)

Date 02-27-2008 06:40 Edited 02-27-2008 06:43

Gerald,

excellent explanations, as usual, and another interesting approach to the topic.

Excuse me when I appear a bit selfish, but regarding my request on a short hint towards the correct headline and terminology for the paper, please allow me to ask your personal opinion.

For finding a "compromise" between the existing terminology would it be "correct" when I state:

"Overlaying (Cladding) of..." ?

I guess that overlaying would point generally to the (welding) process, being used to generate a NiCrMoNb "clad layer" upon a low alloyed heat resistant steel for being protected against corrosive, thermal and erosive impact.

I have great confidence in your judgement and any advice is much appreciated!

Thanks in advance and best regards,
Stephan

By CWI555

Date 02-27-2008 16:49

Stephan,

Good to see you posting again.

My opinion would be that both overlay and cladding could apply to any fusion process. The difference in usage would be in application of the final piece.

If it is for strength and or thermal purposes, then it would be cladding. For instance, Pen stock claddings for mechanical protection against erosion and impacts.

If it is for corrosion protection, such as the example you've given, or for the stainless overlay of a reactor head to protect from boric acid concerns, or other similiar use, then it would be an overlay.

I realize that breaks with convention, but it makes more sense to me than current usage.

Regards,
Gerald

By Stephan (***)

Date 02-27-2008 17:19

Gerald,

once again, a heartfelt "Thanks" for the valuable response!

This makes truly sense...

I will correct the already existing content of the paper by (trying) to use the terms in a more reasonable coherence!

As for the: "...I realize that breaks with convention...".

I mean it was good that someone started to induce an objective discussion about the apparent inconsistency of the present status.

Even this one was Jeff, and I will humble follow him by trying to support his efforts!

Thanks again and my best regards,
Stephan

By js55

Date 02-27-2008 14:33

Gerald,
I see no reason why the etymological history of the words shouldn't be used as a reasoning for deciding usage in applications. It certainly would be a step forward in clarification.
Good discussion.

By jon20013 (*****)

Date 02-27-2008 15:26

I definately agree, ya gotta know the past before you can understand the present and certainly in order to navigate to the future. I love etymology, just never had the time nor patience to study it as some, maybe thats why I'm still living in a cave, lol! Cladding to me is akin to blacksmithing or attaching plates onto ships with rivets, lol!

By GRoberts (***)

Date 02-26-2008 20:21

This is my completely informal opinion/experience, but it seems to be that "overlay" is typically used to refer to the welding process (verb), and "cladding" to the product (noun) regardless of the application method. So you still have the issue of what is applying cladding called when using the non-welding processes? Then cladding seems to be used as a verb. To add to the confusion tough, I see that AWS calls "overlay" a non-standard term, but it is used as a standard term in ASME IX.

However, at least with overaly/cladding, you can generally figure out what the people are talking about since it only involves 2 terms. There is so much mis-communication in the welding arena just because of items like this and worse where many different terms are used to talk about the same exact thing. Imagine taking a wet-behind the ears college educated welding engineer without any field experience, and a ready-for retirement pipline welder/oil rig welder/rod burner (pick your favorite flavor) with 50 years of experience and letting them have a conversation about welding. They probably wouldn't understand 2 words that each-other was saying.

By js55

Date 02-26-2008 21:17

Yeah, the wet behind the ears guy would be like the Rooster in Chicken run listening to the chicken with the Scottish accent. The engineer chicken. "You know, I swear she's speaking english but I didn't understand a single word she said".

Anyhow, I think I understand the logic behind the AWS terms and it is, in my opinion, generated from welding exclusivity where cladding doesn't slam up against a dual meaning. Whereas the industry commonly overlaps, and essentially accomodates quite well. And it is going to be even more critical in the future because that wing of the industry wants to go more to 'cladding' as opposed to 'overlay'.

By Stephan (***)

Date 02-26-2008 21:23 Edited 02-27-2008 06:19

Dear all,

huuh, it's great to see that Jeff was right and I haven't strangled the topic to death before it could breathe and meanwhile some of the greatest experts in the forum have posted their opinions!

What a topic and a great discussion!

I truly enjoy it and I like the explanations, standpoints and instances very much (in particular the last one with the "...wet-behind the ears college educated welding engineer without any field experience, and the ready-for retirement pipline welder/oil rig welder/rod burner with 50 years of experience...".

But please allow me to ask a question since it does "prey a bit on my mind"...

Am I finally even right when I am using a headline like:

"Overlay Welding (Cladding) of..." ? (what I honestly have intended to do).

Or is this - from the technological viewpoint - completely wrong by adding additionally the term "Welding" to the term "Overlay"?

I would really like to avoid creating any nonsense or - what would be even worse - to contribute my share to the apparently already existing confusion.

Or??

Doesn't it even matter at all and I can calm leave it to the reader, by supposing that he/she will certainly be either an AWS- or an ASME member?

I humble request a short advice on this - for me - very important detail and any feedback of you outstanding fellas will be truly and greatly appreciated!

Best regards to all of you,
Stephan