Anything can be welded at virtually any temperature by using pressure.
The Mini Minor crown wheel for the diff started off as a steel disc
cut off from a round billet. This was placed on a mould at the end of
a hydraulic ram, and the other half of the mould was on another
hydraulic ram. To form the crown wheel they were slammed together
under huge pressure - it made a very nice crown wheel - and fast!
SIR - Philosopher unauthorised
You say it started off as a steel disc. You have not mentioned two
pieces which were welded together.
http://www.forging.org/Design/pg6_9.html describes the manufacture of
gears using a similar process to that used for the Mini.
Didn't need to as "welding" wasn't involved in that case - "melting"
was - from a round flat disk to a crown wheel for a diff.
Not quite - the Mini crown wheel blank was not preheated in any
(visible) way at any stage. The process in the URL differs in that
molecular friction alone isn't used to heat the blanks to a momentary
In any event this is wandering off topic at the moment.
SIR - Philosopher unauthorised
But I was discussing welding. You seem to be confusing cold forging
Sorry. There is no melting in either hot or cold forging.
discusses the role of dislocations in metal deformation. Forging is
possible as a result of the mobility of dislocations. All that heating
a billet does is increase their mobility. It is not necessary to cause
melting unless of course one is trying to undertake casting.
No, it appears that there is an issue of splitting hairs into quarters
again. At what point is something "melted"? It appears that it has to
also need the "melted" + "a length of time" to qualify as such.
So if you want to go pick up one of those crown wheels, with your bare
hands immediately AFTER it is made - the same piece of metal you put
into the die BEFORE the event with your bare hand - well go for it,
you say it is "cold" after all!
SIR - Philosopher unauthorised
So "unique" that you cannot find a hole in the arguments I put to you,
instead you find a need attack me personally not only on this but also
"in so many other areas" - your mere assertions amounts to nothing.
Remember the last time you resorted to something like this - can I
just mention "slide rule" to remind you, hmmm?
SIR - Philosopher unauthorised
The question then was whether 43/7 equalled 18/3. I said it didn't.
You insisted it did. I think I abandoned that argument at the point
when you effectively resorted to arguing that 'approximately' is
identical to 'exactly'.
Apart from that, those forging blanks were NEVER hot enough to melt.
It was NOT NECESSARY that they be melted for them to be reformed. One
of the reasons for forging is to presever the original grain flow of
the lank and that would be lost if the blank was melted.
I can no longer recall the number, and care even less - FACT is that
they are close enough to being equal. So in ancient times if they used
shit houses as one set of measurements, and yard arms for the other,
they are close enough considering no fractions were used - a
measurement for which an APPROXIMATE conversions was given - a
measurement for which that level of accuracy is more than adequate.
You came unstuck on that one and still are all at sea with it - as
your recent argument about a nautical mile and "great circle"
circumference measure, which is ANY circle around ANY part of the
globe, when the specific circumference given was at the equator -
nowhere else. Something that varied sometimes by a few meters - like
When ONLY approximates were given then only an approximate can be
VALID and can NEVER mean your petty hair splitting "accurate" claimed
to be achieved FROM an "approximate" - it can't. Simple as that. You
are resorting to the same sort of nonsense game again!!
Prove it! Remember you are talking about a fraction of a second in
time as well.
(I have no idea what relevance "long, limp, and straight" (lank) has
to anything here so I'll ignore the term.)
Not true for the particular example given - other similar items are
cast and machined in the traditional manner. Again you only make
totally unsubstantiated assertions and do not speak about the reason
WHY at all! You know, that thing that makes it work and proves your
claims. Haven't you found it on the net yet?
So let is look at this "grain flow" claim:
This is advertising spoof for a Japanese made Golf club:
"Grain Flow Forging exceeds the conventional forging process by
repeating the high pressure compression process to ensure a tight
uniform grain structure through the clubhead. Each head is forged from
one piece ensuring an uninhibited grain flow through the head and
So there of forging and "grain flow forging" - apparently... but - no
hammering - hydraulically pressed from a single small billet - ie mass
produced by machines where SPEED of production is of prime importance.
Another source says:
"Forging refines the grain structure and improves physical properties
of the metal. With proper design, the grain flow can be oriented in
the direction of principal stresses encountered in actual use. Grain
flow is the direction of the pattern that the crystals take during
So a lot of gobbledegook in reality if compared to your "expert" claim
of "preserves the original grain flow" and "cold". Which is a load of
nonsense for the example I provided - it isn't important. What IS
important is unit speed of production and therefor unit cost of the
production. So slam two dies together and form a crown wheel for a
Mini in a fraction of a second at tremendous pressures like up to
some 50,000 tons and tell me no part of it did melt at any stage! Oh
and you call this "cold forging", when the more correct term is
"Open-die forging" or "Closed-die forging" or even "Two stage
closed-die forging". There is nothing "cold" about it.
Oh and to finish off with the golf club:
"Ageing the head at elevated temperature optimizes strength and
softness." Oh well...... so much for the "cold"....
SIR - Philosopher unauthorised
My apologies. I should have typed
"One of the reasons for forging is to preserve the original grain
flow of the blank and that would be lost if the blank was melted."
it very concisely.
All fairly straightforward.
Nor is there any melting.
700C is elevated but still far below melting.
More than enough of that subject. If you won't learn, then you won't.
Seen it - it doesn't advance your claims at all cnosidering the "grain
flow" is not a consideration.
Nothing there - doesn't discuss the process I mentioned.
So why is it that you are totally unable to explain it?
A parrot on a cage can do just as good as that - therefor it is
arguable the parrot's knowledge is comparable to yours :-)
You cannot know what they have in mind for "elevated" it is a relative
term and all you can relate it to is the melting point. In that case
it is far more likely the "elevated" is far greater then 700C!!
Learn what? You have provided nothing to learn from! On the other
hand, you are in the process of learning youself. Here is another
lesson for you:
"A material exists as a solid when it is below its freezing point."
and "Keep in mind that a material's freezing point is the same as its
melting point." - Steve Gagnon, Science Education Specialist!
Please don't confuse "solid" with "solution" again.
SIR - Philosopher unauthorised
The evidence of porosity is available to the naked eye
in that thin copper flake. There are dozens of tiny bubbles
in evidence, You don't even need a radiograph to see
them. A radiograph or a density test would settle the
matter absolutely, but neither is really needed here as
the sizes and numbers of bubbles already visible are
clear indications of atmospheric melting.
The large numbers of tiny pits in that piece are suggestive
of porosity, but a stereo radiograph, or a density measurement,
would be required to determine if the piece is actually riddled
with porosity, or if we're just seeing corrosion pitting of otherwise
sound copper (if the object is indeed copper, and not a bronze
Pre-Columbian, or Spanish Conquest? I don't see a precise
dating associated with the individual objects. The web site says
the collection of objects date from the Post Classic and Spanish
colonial periods. Also, the web site says the objects are a mix
of copper, copper-tin bronze, and copper-arsenic bronze. What
evidence do you have that the two particular objects you selected
from that collection are pure copper rather than bronze?
You're wrong on both counts. Copper is a malleable, ie plastic, material
even at room temperature. At annealing temperature (500F or greater)
it is much more so. Bubble gum need not be molten for bubbles to be
formed in it, neither does copper. And while copper can be welded, in
an inert atmosphere, by melting, it can also be welded at lower temperature
And wind up with a porous lump of no use to anyone. Really, you haven't
absorbed anything anyone has been telling you about the atmospheric
casting of pure copper.
That's your interpretation. But since your interpretation is wrong, your
conclusion is also wrong.
I don't actually SEE any bubbles at all in the pigs, not even when
magnified to its largest extent - where 1 cm = 3.5 cm on screen.
Now in this item I can definitely see "holes" that you call "porosity"
- and you have difficulty accepting it as cast - despite it clearly
displaying the shape a mould. I would even suggest that this metal was
well overheated when it was cast from the pure look of it.
The items are pre-Columbian from around 1300 AD. They are described as
"Two copper pigs". I accept their view of it being copper.
It is malleable in relation to granite but then so is steel....
Fahrenheit is a long ago discarded temperature measure here and it is
fairly meaningless to me - however the 500F appears to be a
temperature people use to bake cakes or roast a leg of lamb in a
standard domestic oven. I don't even see the copper glowing red from
heat at that point. Naturally annealing can be done at almost any
temperature, but from other things I have read, much much higher
temperatures are in fact used before the term "annealing" is applied
to it. Eg go get the metal red hot.
But one thing that does puzzle me in this claim of yours. A piece of
pure copper, as a result of bringing it up to baking temperature can
cause "bubbles" - forget the baking, take it to dark red state to form
"bubbles". From what does the "bubble" form, we are talking about pure
copper here? How did (whatever) get INTO the copper to form a bubble
in the first place?
Totally irrelevant. But you do point to an external source for the
bubbles by that example - so how does it actually get INTO the copper
in the first place if it isn't (partially) melted?
No it can't. "Pressure" in itself does almost nothing. A loaded
freight train running over a "copper" coin only flattens it and does
nothing else. It is the sudden impact pressure that causes the
molecules to move rapidly, that causes FRICTION, which in turn causes
heat and if sufficient sudden pressure is applied (eg hammer blow to
already hot metal) it CAN melt the material. To "weld" something by
definition requires bringing part of it to a liquid state - ie melted
in the portion being welded.
WELD - verb [with obj.], join together (metal pieces or parts) by
heating the surfaces to the point of melting with a blowpipe, electric
arc, or other means, and uniting them by pressing, hammering, etc -
Though I note that "metals" isn't the only things welded - plastic is
also welded, but the rest applies just the same. It also reminds me of
an axle being welded onto the wheel mounting flange. The axle is
placed against the flange with pressure, and spun very fast. When
suitably hot, the rotation was stopped, added pressure was applied,
the axle was pushed in on the flange by about 1 cm, this to weld it.
This melted the material in the joint part as well as expanded the
The evidence exists that casting was used - Eric Stevens has provided
expert testament to that effect. I have pointed to actual evidence
(such as exists) including in this post. You label cast copper as "of
no use to anyone" when it obviously was of use. You are probably very
right in everything you say -for today's use when high quality melted
copper can he had - but that isn't the issue at all. Frankly, if you
find it "useless" in your endeavours is irrelevant, it doesn't mean
the ancients did. YOU are not them.
You are very quick at labelling "wrong" without a single shred of
proof or alternate theory! I therefor totally reject such
unsubstantiated claims as worthless.
SIR - Philosopher unauthorised
You are wrong, particularly in the case of copper. The power in your
house comes to through a large number of cold welds formed merely by
pressure. This is true irrespective of whether you are supplied via
copper or aluminium cables.
How do you explain the well known welding at ambient temperatures of
precision slip-gauges made of hardened steel? Leave them in contact
overnight and you will be lucky to get them apart in the morning.
--- snip ---
No. While true cold welding can occur, that's not the mechanism(s)
responsible for wringing gage blocks together.
Frankly, the exact details are still in dispute. Part of it is atmospheric
pressure differential between the outside and the area where air has
been forced out from between the blocks. (up to 14 PSI) Part of it is
often due to the stickiness of oil on the blocks. (roughly 2 or 3 PSI)
But neither mechanism is strong enough to account for the amount of
force typically needed to separate the blocks. (typically on the order of
Most experts believe that Van der Waals forces (the same forces that
give water surface tension, or make solder adhere) are responsible for
the bulk of the effect. Others now point to the Casmir force (a quantum
effect). Lively disputes still continue.
A true weld is as strong as the parent materials. (up to 200,000 PSI for
tool steel gage blocks) When you break a true weld, parts of the parent
materials are ripped out. That doesn't happen when separating wrung
gage blocks. So that's not an example of actual welding.
To do an actual weld, the atoms of one piece of material have to be
brought as close to the atoms of the other piece of material as the
atoms of one of the pieces are to each other. At room temperature
this requires a lot of force, on the order of the yield strength of the
This is a few thousand PSI for relatively low yield materials like copper,
or more than 100,000 PSI for materials like tool steel. Of course, as
you increase the temperature, the yield strength of the material declines,
and less force is needed. When a material melts, the yield strength goes
to virtually zero, so little or no force is required to achieve a weld.
You are discussing the underlying welding mechanism. The point is
that, in those circumstances, welding occurs without either heat or
significant pressure, irrespective of whether it is due to Van der
Waals forces, the Casimer force, atmospheric pressure or whatever. I
do know that if such gauges are left in contact for sufficiently long
it is virtually impossible to separate them.
That is very rarely the case.
It depends upon how long you leave them together.
But we (Seppo and I) were discussing welds at ambient temperature. See
Actually, there was nothing inadvertent about trimming the message
of older quoted material which anyone with a proper threaded newsreader
has already seen, and can access again if they care. It is just good
netiquette to only quote enough material to show the statements to
which one is responding.
Not doing such trimming is poor netiquette, and results in deeply nested
reposted material, causing posts to be of excessive length, which are
tedious to wade through to find the relevant new material. Some participating
in this thread seem prone to do that. It is bad form.
Any nesting of quotes greater than two levels is generally excessive, with
rare exceptions. (Complaining about excessive quoting is one of those rare
Now on to the factual dispute.
No, I am not. I'm telling you welding is *not occurring* when gage blocks
are wrung. Perhaps I need to use smaller words and shorter sentences
when trying to communicate with you.
It may be the case when an incompetent is doing the welding, but any
sound weld is as strong as the parent material.
Leave them together until hell freezes over, they still aren't welded.
So, wringing gage blocks doesn't produce forces that even remotely
approach the levels necessary for pressure welding to occur. I thought
that would be obvious in context, but if you need it spelled out in smaller
words, I'll try to oblige.
Indeed, and you used the wringing of gage blocks as an example. It is a
faulty example, as I explained.
I didn't bother to "me too" your good example of copper electrical line
splices, since such piling on is considered bad netiquette.
The pressure generated by the hydraulic swaging tools used by linemen
is sufficient to cold weld clean copper. That was a good example. But your
choice of the wringing of tool steel gage blocks as another example of cold
welding was not. No welding at all is occurring in the latter case.
There is NO weld technique which produces a weld with metallurgy
identical to the the parent metals. ANY weld technique leads to a
discontinuity in material properties in or around the weld zone which
ALWAYS results in a propensity for the welded structure to fail in or
around the weld zone rather than the parent metal.
They are merely immovably stuck together in such a way that it may
require an electron micrscope to detect the interface.
This phenomenon only occurs with precision gauge blocks for the simple
reason that their faces are so flat that the atoms of one piece of
material brought very close to the atoms of the other. When the
interface is broken an electron microscope will show the tears where
the asperities of one surface have welded to another before
No sudden impact is required to create such a weld. Neither is heat,
friction or any other mechanism to cause melting.
Electron microscopy says you are wrong.
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