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Up Topic Welding Industry / General Welding Discussion / Copper inclusions from pre heat torch
- - By jsquat1107 Date 02-05-2010 19:22
I was told that copper inclusions can be introduced by a pre heat torch tip (rose bud) into a plate girder web by the bud coming into contact with the web plate
Parent - - By ravi theCobra (**) Date 02-05-2010 22:24
change to read  "  by the rose bud coming into direct contact WITH THE WEB PLATE  -
Parent - - By ssbn727 (*****) Date 02-05-2010 22:42 Edited 02-05-2010 22:52
And the web plate is hot enough to partially melt and therefore add and introduce the copper inclusion into the plate girder web... If the web plate isn't hot enough or the rosebud has not been ignited to then get the web plate hot enough (Really Important to occur first!), then it's not going to happen!!! :) :) :)

So, the answer to your last question is: "YES but, only if the above mentioned conditions are met and satisfied - CAPECHE???"

Respectfully,
Henry
Parent - - By Metarinka (****) Date 02-06-2010 02:23
Is the uptake temperature for carbon lower than it is for copper? because steels will absorb some carbon at flame temperatures (hence case hardening).  Never heard of copper diffusing below the melting point as it's a substitutional element not an interstitial.

Anyways if your getting hot enough to melt the web plate... you probably are using the rosebud wrong.
Parent - By ssbn727 (*****) Date 02-06-2010 03:21
The melting points are pretty much self-explanatory here... Oh and btw, we're not talking on the atomic level with respect to inclusions within the web plate Joel. ;)

http://www.engineeringtoolbox.com/melting-temperature-metals-d_860.html

Respectfully,
Henry
- - By jsquat1107 Date 02-05-2010 22:41
whatever, is it true
Parent - By waccobird (****) Date 02-06-2010 01:09
jsquat1107
Welcome to the Forum
As Ravi and Henry were trying to explain it can. But I would say that it would only be possible through operator error.
But Welcome
Marshall
Parent - - By DaveBoyer (*****) Date 02-06-2010 03:45 Edited 02-06-2010 03:49
The steel probably should not be hot enough to melt copper, but You could possibly rub some copper off onto the steel surface. This would not be a problem in itself, but if You then welded through the deposited copper the temperature would be high enough to melt the copper, and there is Your copper inclusion.

Moral of the story: Don't rub the rosebud on the work. Using  copper hammers on the workpiece have on ocasion been the cause of copper inclusion.
Parent - - By ssbn727 (*****) Date 02-06-2010 05:26 Edited 02-06-2010 05:35
Hi Dave!

If the web plate is hot enough, yet just below the melting temperature of the steel itself, it would still be able to melt a slight portion of the copper from the rosebud if it were to make contact with the web plate which has a much higher melting point than the copper on the rosebud tip which would indeed cause the inclusion...

A copper hammer could only do that if there were sufficient impact to cause some of the copper to fracture off of the hammer head which could then have enough of the residual copper fragments to form an inclusion after one would weld over it, but there would have to be a substantial amount of copper for this to actually happen because, when the arc and all of it's forces along with the elevated temps from the arc plasma make contact with the usually small amounts of copper deposited when one slightly scrapes a hammer on a carbon steel surface; One would end up vaporizing most, if not all of the very thin deposited layer of copper in a manner very similar to how copper coated GMAW filler wire vaporizes within the arc plasma. ;)

In other words, the conditions, and other variables have to be just right in order for a copper inclusion to occur from either a copper hammer head, or from the tip of a rosebud also. One other thing to remember here... That rosebud tip is not made of pure copper which has a much higher melting point, yet still much less than carbon steel as compared to brass or brass/copper mixes which have much lower melting points. ;)

Respectfully,
Henry
Parent - - By DaveBoyer (*****) Date 02-06-2010 07:52
The copper hammer story was one I heard when Our local AWS group toured Carpenter Steel's Tec center in the late '70s. They are/were big into stainless & other exotic & speacialty steels. The story was concerning stainless steel. One of thier Tec guys was big on finding workplace copper resonsible for causing copper inclusion cracking at grain boundries. Of course this is more of a problem with austinetic steels than it would be with a carbon stel beam.  Copper hammers shed flakes & slivers in use, I have no idea what size particle it takes to initiate the problem.

I don't think the parent metal has to be up to it's melting point for the inclusion to happen, and I doubt that the guy preheating the beam is supposed to take it above 1800f either. As You mention it is not a likely scenario, but not impossible either.
Parent - - By 803056 (*****) Date 02-06-2010 20:20
Simply dragging the copper tip across the surface of the steel, be it carbon or austenitic stainless, can be sufficient to cause some of the copper to be left behind due to the abrasive nature of the rough surface. The minute copper deposits can then be incorporated into the weld if the copper happens to be in the joint or becomes part of the joint.

I've seen welders drag the hot rose bud across the plate, along the joint, and I've seen situations where copper tubing/pipe was stored along side the austenitic stainless tube/pipe in the same rack. Perfect conditions to leave small copper deposits on the surface of the pieces in the rack as one piece of pipe is dragged from the rack.

Carbon steel has a low tolerance for copper. Austenitic stainless steel has even less tolerance for copper. The minute deposits may solidify along the grain boundaries causing cracks due to the CCC (copper contamination cracking). There is an article in a recent copy of the Welding Journal where the wrong filler metal was used leading to CCC problems.

Best regards - Al
Parent - - By ssbn727 (*****) Date 02-06-2010 22:26 Edited 02-06-2010 23:10
Of course this can happen but, it has to occur in a manner where it becomes more than just "incidental contact" or a very slight contact is made for the most part... In other words, if the plate has been overheated enough just below the melting point of the steel, and the rosebud just touches the area where the plate is overheated, then this may or may not occur because, copper does have a lower melting point than carbon steel, and then there has to be enough time passed during the contact period in order for enough of the heat flow from the overheated (Yet less than it's own melting point which will be higher than the copper found in the rosebud) steel to raise the temperature of the copper above it's own melting point to cause a situation where an inclusion can occur... In other words, the conditions, variables must first be met for this to occur! ;0

Another scenario is if an operator intentionally exerts enough pressure to actually scrape enough copper alloy residue from the rosebud onto the surface of the steel even if both components are at room temperature when this actually happens then afterwards, a weld is either deposited either directly or even within a certain close enough distance to the weld zone which will sometimes indeed cause CCC ...However, my point is that the conditions, and variables need to be just right and met for this type of contamination to occur and this does include other metals also...

Btw, I know exactly which article you're referring to Al because I just read it the other day as well, and it also emphasizes that there does have to be enough copper contamination residue whereby even the violent nature as well as the high temperature of the arc plasma is not sufficient enough to vaporize enough of the copper contamination residue in order to prevent CCC. ;) And then the opposite could also occur also whereby there is more than enough of an arc plasma temperature to completely vaporize any of the copper coating found on the filler metal and therefore preventing it from coalescing with the molten steel and solidifying within the grain boundaries to cause CCC.

Respectfully,
Henry
Parent - - By Lawrence (*****) Date 02-06-2010 22:58
Not to mention copper contact tips on GMAW and FCAW guns eh Henry???  :)
Parent - - By ssbn727 (*****) Date 02-06-2010 23:10
You got that right Larry!!! :) :) :)

Respectfully,
Henry
Parent - - By Tommyjoking (****) Date 02-07-2010 01:57
Henry thanks for mentioning the copper coated filler wire....that immediately jumped to my mind here.
Parent - - By 803056 (*****) Date 02-07-2010 04:58
No, I wasn't thinking of the copper flash on the filler metal rod. Actually I was thinking about the article where the welder used the wrong filler metal on stainless steel pipe to make the tack welds. Enough copper was left behind even after the tack welds were removed to cause a problem.

Who knew copper could be so troublesome!

Best regard - Al
Parent - - By ssbn727 (*****) Date 02-07-2010 06:26
Hi Al!

I remember in a previous thread sometime last year regarding the use of a SMO 654 Avesta grade of stainless to be welded on to a carbon steel and one of the participants in the thread would not accept the premise that even minute increases of Cu within the grain boundaries could be one of the reasons why the welds would be more vulnerable to failing due the increased potential of solidification cracking if one did not carefully choose the appropriate filler metal grade for the application:

http://www.bohler-uddeholm.com/english/26_ENG_HTML.php

"Inconel 625 is a  ERNiCrMo-3 as opposed to a ERNiCrMo-13 filler... So if you can find a filler that's close to the chemical composition of the P16 then use it as well especially for "Dissimilar" welding as is your specific application... Also, Inconel 625 has a small amount of Cu (Copper)which may be detrimental to the weld grain boundaries upon solidification when welding the 654 SMO to the carbon steel which is the application the poster described.

What's important as well is this: when the weld is NOT to be subsequently annealed, an overalloyed filler metal should be used... Because of the high corrosion resistance of 654 SMO, the degree of overalloying required is unusually high and so in comparison to Inconel 625 filler, there's not enough Mo for overalloying which is why P16, or a chemical composition equivalent is recommended instead for use on 654 SMO. It's all explained quite plainly and quite clearly in these two .pdf's as well as in the Avesta Welding Manual as well."

http://www.futurealloys.com/654smo.pdf

http://www.outokumpu.com/42534.epibrw

http://www.bohler-uddeholm.cz/czech/files/Prirucka_Avesta_AJ.pdf

Nonetheless, after posting this information up, the person who was really unprofessional towards me for not being a welding engineer, and who in other threads constantly questioned my integrity as well as my understanding and knowledge as well as my own personal experiences in welding and fabricating a very wide variety of different metals, etc... This person was eventually banned fron the forum because he exhibited similar behavior towards other folks in here also which left Ross no choice but to ban him...

Now I may not be a Degreed welding engineer and I never said to anyone here that I was one but, welding engineering principles & practices have been incorporated into my BLOOD for the last FORTY YEARS yet, this individual didn't want to even acknowledge me just on the notion because I wasn't a Degreed welding engineer!!! My response to him was a little more than "Well too friggin BAD!!!" And yet, that's basically what I meant and then some in my response to his ignorance and obnoxious attitude! ;) He could have been an excellent contributor here if he wasn't such a Dip$h!t! ;)

Oh well, some people just don't know any better, and it's kind of like your signature Al: "You can always tell a welder, but you can't tell him much."

All the best to you Al!!! :) :) :)

Respectfully,
Henry
Parent - - By Blaster (***) Date 02-07-2010 20:23
Haha, have you ever met an engineer that didn't mention he was an engineer... usually at least once during each conversation.  ; )

Just a fun poke... not meant to rile any of our beloved engineer members.
Parent - - By 803056 (*****) Date 02-07-2010 22:25
We all like to use a long stick to poke the caged lion on occasion!  ;)

Usually when we get too full of ourselves, someone in the crowd is all too happy to let a little air out of our overblown ego. Welder, inspector, engineer, everyone is fair game in this arena! ;)

Best regards - Al
Parent - - By ssbn727 (*****) Date 02-07-2010 22:35
Is that a cryptic message coming from you Al??? Of all people???

respectfully,
Henry
Parent - - By 803056 (*****) Date 02-07-2010 22:58
It wasn't intended to be cryptic.

You have to admit, no one is spared a jab once in a while in this forum. It is usually in good fun. ;)

I see you must be feeling a little better these days. You respond to a lot of these inquiries with some great leads to more information than any one person can digest. One of these days I'm going to spend some time reading more of them, but atlas, there are just too many to read all of them!

Best regards - Al
Parent - - By ssbn727 (*****) Date 02-07-2010 23:27 Edited 02-07-2010 23:30
And that's exactly where the limits should stay within - Good Fun. Unfortunately, sometimes there have been individuals who come in here like gangbusters, and an attitude to boot who take it way beyond that threshold, and it becomes pathetic after a while to say the least, and that's when John or Ross usually step in and do what they have to do which is very reassuring. ;)

Btw, have you heard about the explosion over at that power plant that's being constructed over in Middletown, CT yet Al? So far from what I've been able to digest so far, is that there was a crew testing the turbines in a combined cycle HRSG natural gas electric power generating facility still being constructed, and I guess they were "blowing down" the piping of the natural gas from the system, and all of a sudden there was an explosion! :(

Last I checked, there were two definite fatalities and many injuries although, they said there were still quite a few folks that were unaccounted for in the accident site...

Thanks for asking! I am feeling a little better, but I'm inundated here with two feet of snow and still trying to shovel out my vehicle which is becoming a pain in the arse and my back as well, so I'm doing just a little at a time in order to avoid putting too much strain on it! ;) Hopefully, I'll be able to free the vehicle out by tomorrow morning! ;)

Respectfully,
Henry
Parent - - By joe pirie (***) Date 02-08-2010 03:04
well what do you say to someone with an IQ of 50 ???   Nice weld
Parent - By 803056 (*****) Date 02-08-2010 04:49
They said there's 5 confirmed dead and 12 injured as of 11:00 this evening.

Sorry to hear you got whacked with so much snow. It sounds like we're in for some this Wednesday.

Be care shoveling that white stuff. I hear it was pretty wet and heavy.

Best regards - Al
Up Topic Welding Industry / General Welding Discussion / Copper inclusions from pre heat torch

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