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Daniel Cauble

Copper inclusion in bloom bar

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So tonight I was consolidating a bloom chunk from a previous smelt, and noticed right off trouble closing cracks.The spark test shows it was bloom steel rather than the normal bloom iron, but surely it should still weld easily enough, especially before the first fold. As I worked the bar, cracks are ever more difficult to close. Even resorted to borax. Some closed, others didnt. Some pieces just had to come off.

 

After a tired evening of hand hammering and fighting this bar, I hit the whole thing with a wire wheel on my angle grinder to shine it up as I always do after working bloom (I like to stare at it!). This time I noticed however, shiny copper is splotches here and there. Sure enough there was shiny copper in a spot where I had to break a small piece off because it did not want to consolidate on the main bar. I think I have dreaded copper in my bloom and it has worked its way to the surface. The only thing I can think of it either we hit a little bit of copper ore, or the copper tuyure ran a little hot that day. Other than that, I have ruled out any other means of it getting there.

 

Question is, will the copper melt its way out? Or is this bar ruined? Google and the search engine here have offered no help. Its ironic because I was just standing next to Mark the other day when he told someone that copper is ruinous to a smelt due to these reasons.

 

I am leaving for the beach in the A.M., and will be back Saturday. Will still check the boards of course, but I cannot take a close-up of these splotches till I get back.

 

Note: That cragginess of this bar is due to the copper I feel. In the past blooms I have worked with, it was never so hard that I could not make a pretty bar for the camera.

10730853_10152373610975009_431321203218943937_n.jpg

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Screw it, I used my phone. It's bothering me. You can make it out. The copper color is not oxidation. This is post wire wheel. Looked at it under 60x and 100x magnification, and its deff. not some funky colored scale.

photo(6).JPG

photo(7).JPG

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Dan,

http://www.bladesmithsforum.com/index.php?showtopic=28695&p=282887

 

I am not sure where the copper came from...I will say some of my early bars in a folding sequence are not good due to overheating the steel ( in order to get the fluxed slag to move out of the metal)........with really clean steel you can get away with doing that for a few folds then go a little cooler.

 

So in your case the copper came from charcoal, the ore......or maybe a spilled bit ..or?

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I would forge it to waffels, restack and weld, fold10 times to see is it totally ruined.

If you find that its not tuyere, ore or other that was in smelting prosses....look in to your charcoal forge..if you used that..Clean it!

Even small amount of Al, Brass, or Copper in CC forge will ruin welding prosses..

If its not ok for blade it would do nice looking tsuba blank, sens patina might be somethign really cool.

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Im using coal. And a different forge that was cleaned out. This particular bucket of coal was stored near copper fittings and there could have been dust from copper oxides.

 

Chances are its not from smelting process. Mark is a master and i havent heard any problems with copper from him.

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I like Niko's idea to turn it into tsuba blanks. I don't think you will be able to fix it for blade steel.

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Daniel, I'm not convinced, at least from those pictures, that you've got copper contamination (but I got some ideas there too).

 

From the pictures it looks more like a very tenacious slag that is brown on the top. Touch it with a file and look with a magnifying glass, and the difference between a colored slag or metallic copper should be pretty obvious.

 

This looks a lot like the slag on the unweldable bloom that resulted when I used the Cowboy charcoal this summer. The slag was basically impossible to knock off the surface, and was greeny brown at the bottom and browny on the top. My best guess is an extemely high calcium content in the slag.

A few years ago I got analyses done on a bunch of bloom samples to see if there was any copper contamination from the tuyere. Out of 11 samples, the only one that had copper contamination was from a smelt with a water cooled tuyere! So the source of copper was either the ore, or copper/brass hardware that snuck into my ore or charcoal (probably the latter).

In that piece, though it welded poorly, the copper was not visible- it was alloyed.

 

If it was metallic copper you could see, it should have burned away at welding heat, shouldn't it?

In the piece that was contaminated with copper, I remelted it Evenstad style, and had that analysed also. The Cu dropped from 2 % in the bloom bar to .25% in the remelted bar.

If the problem is calcium slag, I bet a remelt with plenty of iron oxide would fix that too, or at least improve it. But I haven't tried it (I did not get to keep any of that funky bloom).

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Hummmmmmm??

It was likely Cowboy charcoal we used that smelt.

A couple years ago, I ran into this problem a few times. And it sure looked like copper in the bloom. It would rise to the surface, mix with the flux, and make it a bugger to weld the bloom.
At that time, I figured it was copper from loosing a tiny bit of the tuyere. However, I have seen what looed like copper ore, in some of my roasted brown ore a few times.
One time when we were smelting at Jesus', with Miquel, from Spain, we were looking at the ore under high magnification, nad found some very copper looking deposits.
So, I suppose it could be, that some of my local limonite ore has some copper ore mixed in. But, besides this bloom, from this spring, I haven't been having any problems, and I've been folding dozens of bloom halves up this summer.
I will look for the other half of that bloom, and see if I have worked it yet.

 

Mark

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Velly interestink. I'll be interested to see what you and Dan figure out.
Of course it could be both crappy slag and copper contamination!

This is an excellent example of why it's important to keep good notes and keep your bloom labeled! Otherwise, the mystery would just stay a mystery. ...

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Yea, once i get home in Saturday im hoing to file into the slag/inclusions and peer at it at 100x. Then cut a sliver and see how deep it goes.

 

If i notice it in the heart of the bar, you are more tgan welcome to have a sliver Lee.

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Btw it was this smelt that produced the bloom.

 

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Ok, I found my notes.

Monster bloom of 16 lbs. from 46 lbs. of ore. It was what I had left of the Brazilian ore, and best rocks of the easy ore.
We had the hearth running, so did some re-heats, and press compaction on a big chunk.
I didn't see anything in the notes about loosing any tuyere, but, we got very busy with the re-heating soon after the bloom was cut.

I still have a big chunk of that bloom. I will experiment with it when I get a chance.

Here are a few pics of a bar from the other pure Brazilian ore smelt. It was a bugger to fold up, and wanted to crack all the time. Even after hearth-refining it.

This one here was bad with copper. I quit messing with it.

 

It is just on the very surface. You can't see it in the bar below at all. But when you heat it and flux it, the copper forms on the surface.

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I don't remember seeing any big copper numbers from the analysis of that ore, but it could be why that big pile was never used.

 

 

????

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So weird and fascnating. Now that you mention Brazilian ore it jogs my memory now.

 

Will be interested to see what you find out. If it does seem to be copper i might try a suba blank. If its unweldable slag crap it will make an awesome paper weight.

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I found this note in my black note book...

 

"That cracking in Cu alloyed steels happens when steel oxidies during heating at higher temps and Cu that is
in solution rises up sense its fully liquid and stays under the oxide layer…Molten/
liquid copper goes trough grain boundaries
and during reduction there is tension to the surface and force will tear it….This dosent happen
if heat is under the melting point of Cu.."

 

Quite harsh trans to eng but this might be the case...where ever the origin of Cu might be..

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Given the number of times we have run into this issue with bars from different smelts but which may have in common the NC ores (despite some poor record keeping which has led to some confusions), we have to consider that there is Cu in some of the rocks.

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If we were smelting copper this would be cool (would love to one day). In this case we may either have to figure out how to remove the copper prior to smelting or do so after. Acid treatments? Long periods at welding heat? Good ol hearth refining multiple times?

 

I wonder if there are any ancient books dealing with this problem.

Edited by Daniel Cauble

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From:

 

http://amg-v.com/copperpage.html

 

ROLLING/FORGING The presence of more than 0.2% Cu in steel produces a
characteristic checking on forging surfaces. The degree of this effect
increases with copper and carbon content, and with increasing preheat
time and temperature if heating is done in an oxidizing atmosphere. In
this case, preferential oxidation of iron near the metal surface leaves a
copper-enriched zone containing the low-melting e phase on grain
boundaries. In severe cases, the steel will be hot short and unworkable.
Three solutions to this well-known problem are: (1) preheat only in
protective or nonoxidizing atmospheres; (2) hot work only below 1090C
(2000 F), the melting point of the copper-rich phase; (3) add nickel or
cobalt in amounts equal to about 1/3 to 1/2 the copper content as these
metals raise the melting point of the copper phase. The third solution
is most common, and high copper steels will usually contain some nickel.
As nickel content rises, so does the allowable forging/rolling
temperature, although a practical limit in nickel content is signaled by
the formation of a protective glaze at temperatures above 1280 C (2150
F).



In this same context, it should be noted that copper steels should
never be welded with an oxidizing oxyacetylene flame. This can also
cause preferential oxidation of iron, copper enrichment, and hot
tearing. If oxidizing conditions are avoided, copper steels give
excellent results will all welding processes.

Edited by Lee Sauder

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And so, from the analysis of remelted iron I posted above, a remelt or two should easily get you below .2%.

 

Given the number of times we have run into this issue with bars from different smelts but which may have in common the NC ores (despite some poor record keeping which has led to some confusions), we have to consider that there is Cu in some of the rocks.

But Mark's post above points to the Brazilian ore--

but of course could be both

or tuyere melting-
or junk in the charcoal

 

Junk in the Charcoal would be a good name for a string band.

Edited by Lee Sauder

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Yea this may also be a good candidate bar for some hearth re-melts, turning it into some good steel.

 

Lol, Junk in the Charcoal....

Edited by Daniel Cauble

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The bar that I pictured above should be a good test for the re-melt theory.

I also have a bin hiding somewhere, that has a few more of these copper surface deposits. I always figured these to be a loss of tuyere problem.
But these newer examples are making me think that there is some copper in some of the brown ore rocks from the Easy ore site.
Looking at my records, none of the later magnetite smelts, that I did not mix with Easy ore, have ever had any of the forging problems of this kind.

I have however, processed about 5 full blooms from easy ore smelts, into blades this summer with great results.
I have never noticed any bits of melted copper in the roasting pan, and that may sometimes get very close to copper melting temps.
Now, from May, this year on, I haven't been using any Cowboy charcoal. So, that still is a possible factor.
It may be worth, trying to work these at lower temps a bit. The trouble with that, is it's hard to do any work on bloom material at heats below 2k.

Ah, the fun of working iron from dirt.......................

 

 

Mark

Edited by Mark Green

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Lee, Mark wrote that he mixed the Brazilian ore with the best rocks of his easy ore for that smelt. In my view this all point to copper in some of those NC rocks. It would nice to be able to tell them apart before hand but this is what happens when we use rocks or dirt from the ground instead of clean and purified sources of iron oxide. Each ore source is going to have its own problems. Always costly time-wise as well as use of resources in an already expensive process.

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You think even with all of the success with easy ore that it is the possible factor rather than the Brazilian ore?

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Lee, Mark wrote that he mixed the Brazilian ore with the best rocks of his easy ore for that smelt. In my view this all point to copper in some of those NC rocks. It would nice to be able to tell them apart before hand but this is what happens when we use rocks or dirt from the ground instead of clean and purified sources of iron oxide. Each ore source is going to have its own problems. Always costly time-wise as well as use of resources in an already expensive process.

If I'm reading it correctly, Mark says the pictures he posted are from an all Brazilian smelt, and that the smelt in Daniel's picture is from brazilian mixed with easy brown..

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