Complete failure of a TIG weld...
Ignoramus8601
piece, so that the pipe nipple is perpendicular to the sheet metal.
The objective was to make a little stand on which I would mount a
VFD.
I used about 100 amps of current, DCEN, and ER70 filler rod.
The temperature in the garage was about 40F.
The result was a decent looking TIG weld, nothing to brag about, but
passable.
However, as soon as I stopped welding, the weld zone began to cool
and started making little popping noises. After a minute or two, I
whacked the 16 ga sheet to straghten it, as it was warped a little.
After just one or two whacks, the sheetmetal piece FELL OFF, basically
cleanly, with the entire weld remaining attached to the pipe nipple.
I was completely shocked. After looking at the failure area, I had an
impression that some cracks developed UNDER the weld and a part of the
sheetmetal stuck to the weld, so the weld, sort of, tore off a part of
this sheetmetal piece, as if it cracked in the middle.
I feel kind of fortunate that this was never meant to be a structural
piece, but I get some jitters just thinking about what would happen if
it was.
Would anyone have any clue as to what it could have been.
i
William Wixon
"Ignoramus8601" <ignora...@NOSPAM.8601.invalid> wrote in message
news:EfCdncoiVrsHVYDW...@giganews.com...
i remember seeing a photo of a failed weld like that. was the mounting
bracket for a joystick on a (steve) wittman designed aircraft. was shocking
to see. the article said the joystick fell off in his hand and the guy
managed to fly it safely to a landing, i think it said just as night was
falling. ugh huh?! scary.
i'll let someone more expert than me try to answer your question. i'd think
it would have something to do with the alloy of the sheetmetal.
b.w.
Denis G.
wrote:
This is one of my favorite episodes:
http://funnyvideooftheday.blogspot.com/2006/04/seinfeld-shrinkage-episode.html
Martin H. Eastburn
pipe could screw in.
I did the welding on refractory bricks - and used USA made flanges.
The made in China ones melted like butter and fluff.
I did four welds - doing it across from each other - should have done 5...
I had a large weld to the sheet and it melted into a wide section of flange.
I could take a pipe and attach it - wailing it on the ground. I used a hammer
on the close end - they all worked ok - and delivered two sets of four.
The flanges were something like cast iron. USA was cast iron.
Others were junk metal.
Perhaps mine cooled slower being on brick. The squares (round corners)
were 12 or 18" on a side. Been a while.
Martin
RoyJ
Your weld set up a HAZ in the sheet metal that cooled very rapidly, made
it extremely brittle. Since the pipe was much thicker, it doesn't get
anywhere near the stress levels that the thin stock will see. The
popping noises were the stress cracks starting to develop.
You could test this scenario by heating a chunk of the sheet metal to a
high temp (yellow orange) and quenching hard in water. If it gets really
brittle (snaps when bending it 90 degrees with a pliers), you have found
the culprit.
We had a project that used 1/4"x2" bar stock that got welded and then
cut through the weld. Worked fine for years, one day we tore up 3
bandsaw blades in an hour. I traced it down to ONE STICK of bar stock
that had a carbon content well above the normal hot rolled.
cl...@snyder.on.ca
When welding thin stuff to thick stuff, preheat the thick stuff first.
With Tig, it's easiest to preheat with Oxy-Acet.
A GOOD tig welder can get the base metal of the heavy peice up to temp
with just the tig torch without burning the thin material through, but
it's tricky and takes more than a little practice.
Also, shop should be above 60F with still air. At 40F the joint will
cool fast.
Steve B
"Ignoramus8601" <ignora...@NOSPAM.8601.invalid> wrote in message
news:EfCdncoiVrsHVYDW...@giganews.com...
I have seen thin wall tubing do that when welded to a piece of plate. You
need to keep the heat on the thick part almost entirely, and let the
accumulation of the molten puddle wash down on to the thin metal until you
"see" fusion. It is best done in a flat position. But then, at that moment
the hotshortedness of the metal will occur in an instant, and if you're too
slow, it will blow a hole. Hotshortedness (sp?) is when a metal collapses
under its own weight when it reaches molten temperature. Either that, or
maybe there was some coating on the sheet metal that created a barrier to
fusion. As suggested, I'd try preheating, and doing it in a little warmer
circumstances.
Hot-shortness on Google: ('h�t 'sh�rt�n?s)
(metallurgy) Brittleness, usually of steel or wrought iron, when the metal
is hot, due to a high sulfur conten
Steve
Ed Huntress
"Steve B" <desert...@dishmail.net> wrote in message
news:9651v6-...@news.infowest.com...
Steve, not to contradict your instructions, which sound like what
instructors have told me about welding thin to thick pieces, but that's not
actually what hot-short means. Hot shortness occurs well below melting
temperature, and it's a complete loss of strength in the metal at that lower
temperature. It's taken advantage of, for example, when breaking up iron
castings into smaller pieces for scrap, often for feedstock in casting. When
the metal becomes hot-short, a whack with a hammer, that ordinarily wouldn't
do a thing, suddenly is able to break the metal into small chunks.
It's brittleness, as the definition says, not a molten state.
--
Ed Huntress
Steve B
"Ed Huntress" <hunt...@optonline.net> wrote in message
news:4b1de94d$0$4989$607e...@cv.net...
I had heard the term used when aluminum is there one instant and on the
floor the next. Heated past the melting point, then turns to liquid and
collapses. I had never heard that sulfur content had anything to do with
it, tho. Either way, I'm sure there's a reason it didn't stick. Has to be.
I'll ask my old welder friend tomorrow and see what he says. He's pretty
sharp.
Steve
Ed Huntress
That's true, but it's because most aluminum alloys have distinct liquidus
and solidus temperatures that are very close together; they have no "pasty"
range, or none that you'd notice. You can equate this to various solders;
some electrical solders behave just like that, but the alloys made for
wiping plumbing joints or for automobile body solder are the opposite --
they get pasty and stiff, and then pasty and runny, and then they finally
slump and run.
The other reason this is remarked about with aluminum in welding
applications is that the liquidus temperature is below the temperature at
which the metal glows red, so you have little warning when it's about to
turn to liquid and collapse. People who weld it a lot become sensitive to
other signs, mostly surface appearance. With steel, the red, then yellow
glow help you to see where you stand.
Some aluminum alloys are indeed hot-short, but I don't think it has anything
to do with sulfur in this case. It may be the copper in 2000-series alloys.
It's one reason that 2024 is so difficult to weld successfully; as it cools
and shrinks, it quickly passes through the hot-short range, and that's when
it's likely to crack and tear. It's also a problem with some grades of
steel; which ones, I don't recall.
Terminology in these trades is kind of a mess, and if someone is calling the
sudden melting of aluminum "hot shortness," they're misapplying the term. It
happens when the metal is very hot but still in the solid state. It's a
tearing or cracking, rather than melting or slumping.
> I had never heard that sulfur content had anything to do with it, tho.
> Either way, I'm sure there's a reason it didn't stick. Has to be.
> I'll ask my old welder friend tomorrow and see what he says. He's pretty
> sharp.
>
> Steve
As for the sulfur, I don't remember. It's been years since I was really up
on the details of metals behavior. And I'm a pretty crude and amateurish
weldor, so I can't help there, either.
--
Ed Huntress
Jim Wilkins
wrote:
Jim Wilkins
wrote:
> However, as soon as I stopped welding, the weld zone began to cool
> and started making little popping noises. After a minute or two, I
> whacked the 16 ga sheet to straghten it, as it was warped a little.
I TIG welded mild steel plates across the ends of 1/2" drill rod and
had a similar problem, the high-carbon steel cracked in the heated
zone beside the weld. I knew it could happen but didn't want to heat
and roughen the drill rod too much because it was pivot pins. After a
few experiments I found that keeping the puddle molten until the dark
blue color had run down the drill rod at least half an inch from the
weld was enough.
jsw
Steve B
"Ed Huntress" <hunt...@optonline.net> wrote
> As for the sulfur, I don't remember. It's been years since I was really up
> on the details of metals behavior. And I'm a pretty crude and amateurish
> weldor, so I can't help there, either.
>
> --
> Ed Huntress
Not to worry. I've seen lots of darn good welders who couldn't carry an
intelligent conversation about metallurgy or terms but could pass x-ray
every time. Not to mean that you aren't conducting an intelligent
conversation, but really, even "crude and amateurish" weldors can get stuff
to stick, and stick for a long time. After that, it's aesthetics, unless
it's for inspection. I've found some old stuff welded together that's been
stuck for decades. Gorilla welds, I call them. But they're still stuck
fast. My dad used to call them mud daubers.
Steve
Ignoramus10187
> I have seen thin wall tubing do that when welded to a piece of plate. You
> need to keep the heat on the thick part almost entirely, and let the
> accumulation of the molten puddle wash down on to the thin metal until you
> "see" fusion. It is best done in a flat position. But then, at that moment
> the hotshortedness of the metal will occur in an instant, and if you're too
> slow, it will blow a hole. Hotshortedness (sp?) is when a metal collapses
> under its own weight when it reaches molten temperature. Either that, or
> maybe there was some coating on the sheet metal that created a barrier to
> fusion. As suggested, I'd try preheating, and doing it in a little warmer
> circumstances.
SteveB, I thought about this overnight.
I think that this steel sheet was a bad specimen, and it had
lamination issues and some sort of hot-shortedness or high carbon
content, in the local place where I attempted welding.
SteveW, it was definitely hot rolled, with plenty of mill scale (which
I wirebrushed away prior to welding).
This is very scary. I thought that a half decent looking TIG weld was
guaranteed to have fusion. Now, I do not know how to tell a good one
from a bad one.
i
Ignoramus10187
> I'll suggest that the sheet metal was high carbon, cold rolled stock.
> Your weld set up a HAZ in the sheet metal that cooled very rapidly, made
> it extremely brittle. Since the pipe was much thicker, it doesn't get
> anywhere near the stress levels that the thin stock will see.
The sheetmetal was definitely hot rolled, with typical mill scale.
> The popping noises were the stress cracks starting to develop.
Definitely.
> You could test this scenario by heating a chunk of the sheet metal to a
> high temp (yellow orange) and quenching hard in water. If it gets really
> brittle (snaps when bending it 90 degrees with a pliers), you have found
> the culprit.
>
> We had a project that used 1/4"x2" bar stock that got welded and then
> cut through the weld. Worked fine for years, one day we tore up 3
> bandsaw blades in an hour. I traced it down to ONE STICK of bar stock
> that had a carbon content well above the normal hot rolled.
Yep.
i
Ignoramus10187
> On Dec 7, 10:31?pm, Ignoramus8601 <ignoramus8...@NOSPAM.8601.invalid>
Jim, in your case, what cracked was the drill rod, right?
i
Cydrome Leader
how about hit them with a hammer?
Ignoramus10187
Well, there is always doubt as to whether I hit it hard enough or
not.
i
Cydrome Leader
Just give up then, testing stuff is too hard, don't even bother.
Dr Argentum
hot rolling where a small amount of liquid forms at the grain boundaries
and the material falls apart. It doesn't take much liquid and can be a
couple hundred degrees below the melting point. I doubt that this is
the case here as it is hot rolled stock, and mills don't like it when a
several ton billet flies out in small bits. (Well ok, it's poetic
licence.) Sulfur is usually the culprit in these cases, but there are
oddball elements that can cause a similar effect.
The advice on heating and quenching is a good practical test. It is
likely a higher carbon content. What was the result?
I've lurked here for years. I taught a course for a few years on the
metallurgy of welding and it helped me to read the adventures of welders
and get a sense of reality. I'm happy to finally be able to chime in....
Ken
Ignoramus10187
> Steve B wrote:
>> "Ed Huntress" <hunt...@optonline.net> wrote
>>
>>> As for the sulfur, I don't remember. It's been years since I was really up
>>> on the details of metals behavior. And I'm a pretty crude and amateurish
>>> weldor, so I can't help there, either.
>>>
>>
>> intelligent conversation about metallurgy or terms but could pass x-ray
>> every time. Not to mean that you aren't conducting an intelligent
>> conversation, but really, even "crude and amateurish" weldors can get stuff
>> to stick, and stick for a long time. After that, it's aesthetics, unless
>> it's for inspection. I've found some old stuff welded together that's been
>> stuck for decades. Gorilla welds, I call them. But they're still stuck
>> fast. My dad used to call them mud daubers.
>>
>> Steve
>>
>>
> In the steel industry, hot shortness is used to describe failure during
> hot rolling where a small amount of liquid forms at the grain boundaries
> and the material falls apart. It doesn't take much liquid and can be a
> couple hundred degrees below the melting point. I doubt that this is
> the case here as it is hot rolled stock, and mills don't like it when a
> several ton billet flies out in small bits. (Well ok, it's poetic
> licence.) Sulfur is usually the culprit in these cases, but there are
> oddball elements that can cause a similar effect.
>
> The advice on heating and quenching is a good practical test. It is
> likely a higher carbon content. What was the result?
>
> I've lurked here for years. I taught a course for a few years on the
> metallurgy of welding and it helped me to read the adventures of welders
> and get a sense of reality. I'm happy to finally be able to chime in....
>
> Ken
Ken, I have retained that piece and the test seems easy enough: get it
red hot and plunge into cold water, then bend.
I will take some pictures, one of which would be of it prior to
testing (but with evidence of a failed weld) and then the results of
testing.
i
Jim Wilkins
>
> Jim, in your case, what cracked was the drill rod, right?
>
> i
Yes, a brittle, crystalline fracture right under the initial 1/4" plug
weld, which I had filled quickly. These were the pivot pins and the
retaining plates for my front end loader.
jsw
Jim Wilkins
10187.invalid> wrote:
> On 2009-12-08, Dr Argentum <dr.argen...@hotmailhotmail.com> wrote:
> ...
> Ken, I have retained that piece and the test seems easy enough: get it
> red hot and plunge into cold water, then bend.
>
> I will take some pictures, one of which would be of it prior to
> testing (but with evidence of a failed weld) and then the results of
> testing.
>
I posted a simple demo of hardness vs elastic modulus once that
involved bending hard and annealed bugle head screws held by their
points in a vise. The difference was very obvious between the two, but
without an identical reference it's difficult to compare. In this case
you could cut three pieces, harden two and anneal one of those, then
bend all three. The annealed one represents what you can do to fix it
after welding.
jsw
Ed Huntress
"Dr Argentum" <dr.ar...@hotmailhotmail.com> wrote in message
news:4b1ecdee$1...@win9.rmc.ca...
Good to see you here, Ken. You might be interested in this brief piece on
hot-shortness. It's all a little fuzzy:
http://adsabs.harvard.edu/abs/1980RSPTA.295...89M
--
Ed Huntress
fran...123
> This is very scary. I thought that a half decent looking TIG weld was
> guaranteed to have fusion. Now, I do not know how to tell a good one
> from a bad one.
>
> i
would you consider doing exactly the same thing an inch or so away with some
of your tig compatible bronze and tell us if you get the same failure?
Seems there was a thread with that in it just lately around here.
not everything is weld able. There are ways to make sparks off metals and
examine what you get but sometimes just the four and a half inch grinder and
a piece of known structural mild steel as a control can give you an idea if
what you have isn't mild steel. The first guy also told you how heat it
quench it bend it.
Fran
not cross posted
F Murtz
nipple was hot enough.Was the sheet on a steel bench that would take the
heat from the sheet. Barring that it could be two dissimilar metals.
Ernie Leimkuhler
Most pipe is made overseas with very poor quality control as to
metallurgy.
As long as the pipe holds pressure, it passes.
My suspicion is the pipe was bad steel.
In article <EfCdncoiVrsHVYDW...@giganews.com>,
Ignoramus20864
> Was the nipple cast or machined?
machined (cut threads).
> Most pipe is made overseas with very poor quality control as to
> metallurgy. As long as the pipe holds pressure, it passes.
>
> My suspicion is the pipe was bad steel.
Maybe, but the weld clung to pipe very well, and broke off near where
it made contact with the sheet metal.
i
Gunner Asch
<ignora...@NOSPAM.8601.invalid> wrote:
>I tried to TIG weld a 1/2" pipe nipple, to a 16 gauge sheetmetal
>piece, so that the pipe nipple is perpendicular to the sheet metal.
>
>The objective was to make a little stand on which I would mount a
>VFD.
>
>I used about 100 amps of current, DCEN, and ER70 filler rod.
>
>The temperature in the garage was about 40F.
>
>The result was a decent looking TIG weld, nothing to brag about, but
>passable.
>
>However, as soon as I stopped welding, the weld zone began to cool
>and started making little popping noises. After a minute or two, I
>whacked the 16 ga sheet to straghten it, as it was warped a little.
>
>After just one or two whacks, the sheetmetal piece FELL OFF, basically
>cleanly, with the entire weld remaining attached to the pipe nipple.
>
>I was completely shocked. After looking at the failure area, I had an
>impression that some cracks developed UNDER the weld and a part of the
>sheetmetal stuck to the weld, so the weld, sort of, tore off a part of
>this sheetmetal piece, as if it cracked in the middle.
>
>I feel kind of fortunate that this was never meant to be a structural
>piece, but I get some jitters just thinking about what would happen if
>it was.
>
>Would anyone have any clue as to what it could have been.
>
>i
ayup..it should have been brazed, rather than welded. The heat treating
you gave it with the TIG made it brittle and as the sheet metal cooled
much much faster than the stud...shrug
Next time if you MUST tig it..hold a OA torch on it and then
slowly..slowly turn down the heat as you anneal it directly after
welding it with the tig.
Shrug
Metals are interesting when you do odd stuff.
Gunner
"First Law of Leftist Debate
The more you present a leftist with factual evidence
that is counter to his preconceived world view and the
more difficult it becomes for him to refute it without
losing face the chance of him calling you a racist, bigot,
homophobe approaches infinity.
This is despite the thread you are in having not mentioned
race or sexual preference in any way that is relevant to
the subject." Grey Ghost
Bruce L. Bergman
Heck, just the 40-F room temperature could have been a major
contributor to the failure, especially if there was a breeze. When in
doubt, preheat the workpiece before welding, and let it anneal and
cool slowly after...
Iggy: Got a small blacksmiths's forge? A propane weed-burner and a
stack of firebricks is all you need for a makeshift forge. Two
layers for the floor and base, two walls, and a little arch over the
center, aim the weed burner in one end and stick your work in the
other with fireplace tongs. It will concentrate the heat nicely.
--<< Bruce >>--