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Hi everyone, I thought I'd use this post to introduce myself. I started smithing about three months ago. As I began messing around, I quickly found out what the term "burnt iron" was. 

 

I work in the lab of a grey/ductile iron casting foundry in NEPA, under a fantastic and very experienced metallurgist. He has been helping me along throughout my progress, but with my question concerning burnt iron, he couldn't help (he had never heard the term). 

 

So last weekend, while working in the forge, I purposely burnt the end of a rod, bringing it to its liquidius temp (honestly didn't think I could do that). I cut two pieces: one burnt and one untouched. The microstructure of the untouched steel shows constant grain boundaries, while the other was disturbed, air-quenched, changing it to martensite and/or bainite, depending on the layer. Basically, as far as I could understand, the force of oxygen combined with the carbon, which cause a loss therein, disrupting the grain boundaries. 

 

I am far from a metallurgist, just a lab rat. If you guys have any further input, I'd really appreciate..correct me if I'm wrong. 

 

Burnt

post-39206-0-52716000-1365791730_thumb.j   

 

Untouched 

post-39206-0-55254400-1365791716_thumb.j

 

I also ran a 1/2 gram sample in out Leco carbon and sulfur analyzer, and found that the untouched steel contained .326% carbon, and .125% carbon burnt. 

 

This forum is great, and I hope to learn/contribute more. 

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As far as I know, the most mild steel starts at .3%. Wrought contains the lowest, starting at about .1%. I am going to run three samples of both again on Monday immediately after a standard to obtain an average. A larger piece will be run on our spectrometer for a more accurate understanding. 

 

I am not an expert on steel. I came out of nowhere in this business, so I still have much to learn. 

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Like the post, like the pics. Maybe wrong, but thought steel ran from .5 to 2% carbon, wouldn't .326 be wrought iron?

Wrought iron has little or no carbon, .326 would be a low carbon steel.

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Welcome aboard, glad to have you Porkchop.

 

0.326% is 32.6 points of carbon and about mid range of low carbon/mild steel. The burnt being around 12 points is close to wrought for carbon content. All it really needs now is some silica.

 

I'm thinking you'll be able to settle some questions we've had for a long time. It's GOOD to have a lab rat on board! REALLY GOOD!

 

Frosty The Lucky.

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Very low carbon steel is used for deep drawing, like lawn mower decks and oil drums, and would be designated 1008 or 1010. Eight points of carbon would be .08% by weight.  Barely noticeable hardening even with extreme quenches. It costs extra because you have to get the extra carbon and tramp elements OUT of a scrap melt. But its use means less wear and tear on forming dies, and better complex shapes can be produced without stretches or tears.

 

Ordinary low carbon steel is 1018 or 1020. It is what we used to be able to get in architectural shapes before A36 became the standard, and why old-timers would say that you could not harden mild steel into tools.

 

A36 is like Roach Coach dining, don't ask what is in the food at a construction site lunch truck, it's cheap and filling, if not nutritious.

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Frosty, I'd be more than happy to contribute. If there is nothing I can answer, I'd be more than happy to present the question to my boss. He is nearing the end of his career, and loves the fact that someone is actually interested, instead of just going through the motions, so he is eager to share his knowledge, and lights up each time I ask him a question. 

 

**Not to add to his merits, but he was a Bethlehem steel metallurgist until the very end.

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As far as I know, the most mild steel starts at .3%. Wrought contains the lowest, starting at about .1%. I am going to run three samples of both again on Monday immediately after a standard to obtain an average. A larger piece will be run on our spectrometer for a more accurate understanding. 

 

I am not an expert on steel. I came out of nowhere in this business, so I still have much to learn. 

Wrought iron can be allover the road as far as carbon content.  It was not made with modern quality controls what really makes something wrought iron is a fibrous structure running the bar.  I have had wrought iron bars that spark tested as mild steel but when cut half way through and snapped it showed the heavy wood like grain. 

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Wrought iron is not defined by its carbon content but by its method production and the fact that it contained iron silicates as a by-product of its production techniques. Wrought iron was routinely carburized to product higher carbon contents for applications that needed that. This was typically called blister steel, and though the carbon content was high, the iron silicates remained in the material. For certain applications, these iron silicates would cause rapid part failures (spring and razors being two examples). For applications such as this, the blister steel was melted to allow the iron silicates to float to the top of the bath of molten metal. This liquid steel was cast into small ingot mold and re-forged. Steel produced by this method was referred to as "cast" steel  even though the end products produced were still forged to shape. This designation allowed users to distinguish high quality tools and objects from those made strictly of high carbon wrought iron.

 

The microstructure of the "untouched" piece shown at the beginning of this thread is ferrite/pearlite combination that is typical of all carbon steels will less than 0.77% carbon that are slow cooled from hot working temperatures, as is the case for bars of A36 and similar supplied in the hot rolled condition. The relative amounts of pearlite/ferrite will vary depending upon the carbon content. More carbon=more pearlite. Baintie/martensite are formed when steel is cooled more rapidly from hot working temperatures.

 

Patrick

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Criminetley! Are we using the decimals properly? Patrick did. For example, the zero in front of the point seventy-seven indicates 77/100 of one percent.

 

Wrought iron is iffy, but I think a lot of the old iron furnace product was 0.01 to 0.02% in carbon content. Baling wire might be about 0.10%; I'm guessing. A36, so called "mild steel" is more concerned with performance, yield, tensile strength, etc.,The carbon range may vary from about 0.23 to 0.28% carbon. A36 has a manganese addition. A36 is an American Society for Testing Materials number, not a Society of Automotive Engineers number.

 

In plain carbon steel, mild steel is 0.10 to 0.30%; medium carbon steel is 0.30 to 0.55%; high carbon is 0.60 to 1.3% (commercially).

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Hi welcome to this great site

 

thanks for sharing this info it is very interesting 

 

it would be very fascinating if you could do the same test with some high carbon steels like 1095, 1080, O1 or such if you could get your hands on some bits of on of them

 

these steela will also burn at much lower temperatures and with more sparks 

 

this is steels commonly used by knifemakers 

 

If i didn't live on the other side of the pond I would be more then happy to send you some known steel bits to test out, maybe another knifemaker who shares your continent would be as kind ?

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Frosty, I'd be more than happy to contribute. If there is nothing I can answer, I'd be more than happy to present the question to my boss. He is nearing the end of his career, and loves the fact that someone is actually interested, instead of just going through the motions, so he is eager to share his knowledge, and lights up each time I ask him a question. 

 

**Not to add to his merits, but he was a Bethlehem steel metallurgist until the very end.

 

 

We're more than happy to have you here with or without contributions. You do however make a really valuable resource available so you get a gold star.

 

Everybody, well almost everybody, likes to know if their trade is of value to others. Folk doing things like making steel are a little behind the shades and very few even know the job is being done. If we can help you put a smile on your boss's face while we reap the benefits of his and your experience it's a WIN WIN!

 

Frosty The Lucky.

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DClaville, I can test anything I can get my hands on. In less than five minutes I can get a detailed report from the spectrometer which calculates the percentage of 20 different elements without destroying the piece. As I continue delving into this trade, and when I stumble upon something of that grade, I will surely do so. The fab shop down the road from me has been surprisingly generous in helping me with obtaining stock at a decent price (they seem to love artists). I'm sure they can through me a scrap punch or something of the sort. On my next trip I'll ask. 

 

Frosty, I appreciate your kind words. It makes going to work much more worthwhile at 4:30 in the morning  :D

 

On the subject of anonymity, I will refer to him as J from here on out. 

 

I'm glad I can be of service!

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Thanks Patrick, I was getting all het up about how off a lot of the answers were.  Guess that metallurgical degree didn't hurt you after all; save for the urge to buy bigger powerhammers it seems to have given you!

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I work at a refinery in the Pressure Equipment Integrity area.   Basically that means that we deal with Metalurgy selection, corrosion mechanisms and unfortunately failure analysis from time to time.   One aspect of failure analysis is to take a failed piece of metal and polish and etch it in order to look at the microstructure and grains/boundaries.    I'll see if I can get these pics in front of a couple of Materials and corrosion engineers to see what they have to say.   "Burnt" metal would certainly represent a failure.   

 

On the other hand it may be that just visually looking at burnt steel it becomes obvious that it is ruined and so maybe these guys have never seen the microstructure either.   We usually don't do much analysis on stuff that is clearly ruint.    Let me get back to the forum on this...   If I don't forget...   CRS....

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