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Old 10-11-2017, 12:46 PM
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Default carbon steel

Hello all, is there an easy test to find out if the metal contains carbon. also, how high of a carbon content do you need to make a fire striker? thanks
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Old 10-11-2017, 04:03 PM
AussieTom AussieTom is offline
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Might be a good question for Ozwelder if he is around.

Im going to say all metals you find around that rust are going to have carbon in them. Pure iron is essentialy useless and just not available. Mild steel will have around .05% carbon along with other alloys, and is the most common steel you will find, is ductile and malleable. Cast iron will have around 5% carbon, its very brittle and shows dull grey along its fracture surfaces.

I didnt know carbon was needed for spark generation? I always thought the caveman recipie was flint rock and iron ore rock, bang together = fire!

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There you go D***head Doug, FIXED!

Last edited by AussieTom; 10-12-2017 at 09:28 PM.
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Old 10-11-2017, 04:38 PM
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Quote:
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Mild steel will have around .5% carbon
It does ?
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Old 10-11-2017, 04:40 PM
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It does ?
Yeah, maybe not. .05% might be closer

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Old 10-11-2017, 05:42 PM
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Stamped or deep drawn steel is low in carbon, as it works more easily. < 0.1%. Then typical structural steels which may run from about 0.15 - 0.30%. Easily weldable, no particular worries about hardening or brittleness.

A fire striker should be very hard on the striking surface. Something with about 0.8 to 1.0% carbon, heated & quenched. Or use a bit of an older, quality file. (Some newer files are case hardened.)

1095, W-1 or O-1 steel would do the trick.
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Old 10-11-2017, 08:39 PM
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The easiest test to see if a steel has much carbon is to do a spark test. If you touch it to a grinding wheel and sparks stay in one piece and travel a long way there isn't much carbon. If sparks split off and the spark trail has a lot of forks in it, then you have carbon. The spark trail from grinding high carbon steel has a kind of fuzzy look to it.

Beyond the spark test the next thing to do is to heat a sample piece until it is non magnetic and quench it. Then you can test it with a file to see if it hardened or you can break it and look at the grain structure. High carbon steel should snap cleanly and have a grain that looks very fine like talcum powder, after being quenched.

A good striker should be as hard as a knife blade. You want it hard enough that it doesn't just dent or tear, otherwise you won't get sparks from it.
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Old 10-11-2017, 08:59 PM
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Quote:
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Yeah, maybe not. .05% might be closer

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Maybe you just stop guessing.....Hmmm ?
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Old 10-11-2017, 09:22 PM
AussieTom AussieTom is offline
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Maybe you just stop guessing.....Hmmm ?
And the troll comes out from under its bridge........

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Old 10-12-2017, 07:47 AM
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Here is an Iron-Carbon Phase Diagram for steel. I am borrowing it out of course materials from a class I took at OSU, hopefully they don't have a problem with that

As you can see across the bottom, steel can have a carbon content anywhere between zero, and 2 percent.

The line designated at .8 percent carbon is the eutectoid line. At room temperature this is the difference between the crystal structure being ferrite + pearlite, vs. cementite +pearlite. That isn't important to the average person, but if you have ever heard the term eutectoid or hypo eutectoid that is where it comes from.

What is important to the average blacksmith is the austenite range, which is the diamond shaped zone in the upper left. Austenite is formed when all of the carbon has dissolved into solution, and coincidentally the steel turns non magnetic while it is in this state, which gives us a surefire way to know we have reached the right temperature.

Austenite is not actually useful for tool making. It is soft. If you find a stainless steel that is labeled as an "austenitic stainless steel" for example, it has enough alloy in it that it is austenitic at room temperature. It will be too soft to use for things like knife blades etc and cannot be hardened beyond work hardening which is only useful if you like to ruin drill bits.

The useful thing about austenite is that when we cool it down really fast, the carbon is trapped in a matrix called Martensite. Martensite is the hardened form of steel, and is what we need for knives, chisels, axes etc.

As a general rule, the carbon content will dictate how hard the steel can get. All steel with carbon is hardenable, but not to the same extent. Steel up to the .40% range can actually still be machined fairly easily after being hardened and are used a lot in things like gun parts. For a hatchet head that needs to be tough you might get away with steel in the .50% range, but for knives or chisels and other cutting tools you really want to stay in the .60%-1% range.

You also have the benefit of being able to temper steel and draw its hardness back to wherever you want it. So it's generally better to work with high carbon steel that can be hardened beyond what you want, than it is to use lower carbon and hope that you can achieve its maximum hardness. O1 straight out of the quench for example may have a hardness of RC64 or more, and you can dial that back as far as you want by tempering. 1040 may only come out of the quench at RC40 and there is nothing you can do to make it RC55.
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File Type: pdf iron carbide.pdf (529.1 KB, 27 views)
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Old 10-12-2017, 07:57 AM
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Quote:
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And the troll comes out from under its bridge........

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No, your the google searching cut & paste some words you found under a rock
troll.

Your posting WRONG INFROMATION.

If you don't what the carbon content of Mild steel is, don't "wing it".
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