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Adriaan G

Mild steel test

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There's two ways that I can think of. 

The first would be to heat it to critical and quench it.  If it hardens it is high enough carbon to make a blade from, if it doesn't then it's not. 

The second would be to spark test it.  I'm not good enough at it to speak with authority about the ins hands outs, but you can Google it and get a pretty good idea.

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To piggyback on Alex's comment.  After you quench the steel strike it with an hammer.  If it shatters like glass then it has enough carbon in it to make a blade.

With the spark test it's best starting out to have some known steel samples to compare the spark pattern to.  Get some of whatever they've go at the hardware store for low carbon steel and then some medium and then high carbon steel.  If you don't have any samples around the shop you can buy short pieces for stock removal from someplace like Jantz or Midwest Knivemakers Supply.

The best idea is to start out with a known steel in the first place.  That will take a lot of work out of figuring out the heat treating routine.

Doug

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This should give you a good idea. 

 

post-1230-1214904317.gif

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The spark test can be difficult to figure out at first, and it requires a powered grinder of some sort.  Hard wheels are best, but belts work too.

The quench test is the usual one, especially once you've figured out by the spark that it's high carbon.  Forge a long thin point on a rod, heat to orange, and quench in water. Don't hit it with a hammer, that's kind of dangerous (shrapnel effect).  Put the tip of the rod in a vise and try to bend it.  If it has cracked in the quench or snaps off the minute you clamp it, it's an oil- or air-hardening high carbon tool steel.  If it snaps clean, it's hardenable steel.  If it bends a bit before it snaps, it's a lower carbon that may be good for tools, but not knives.  If it just bends and doesn't break, it's very low carbon indeed.  

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Is there a spark tests to figure out if something is wrought iron?

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Wrought sparks like low-carbon mild.  The test for wrought is to saw a bar about halfway through, then bend it over on itself.  if it shears with a noticeable fibrous look (as opposed to crystalline), it's wrought.  Old rusty wrought like wagon tires that have been outdoors for years will show a distinctive woodgrain-looking pattern in the rust, like this anchor in Cornwall:

20150806_101002.jpg

 

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That anchor is so cool. Would make one helluva decor piece... :ph34r:

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Spark test can get thrown off by high carbide steel like cpm 3v or s35vn, the high end stuff. Vanadium, tungsten, mollybdenum ect in higher amounts does awkward things. Works pretty good for telling what it is in most other stuff.

You can also tell by a quench test, of if it harden able or not. if it isnt its usually under .35% carbon.

Edited by Joe Wulvz
misplaced the decimal for the .35 carbon

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On 12/9/2018 at 2:49 AM, Joe Wulvz said:

Spark test can get thrown off by high carbide steel like cpm 3v or s35vn, the high end stuff. Vanadium, tungsten, mollybdenum ect in higher amounts does awkward things. Works pretty good for telling what it is in most other stuff.

You can also tell by a quench test, of if it harden able or not. if it isnt its usually under 35% carbon.

Where did you come up with that number (35%)?

most generally, good hardening starts around .6%. That is why 1070-1085 are the basic simple steels. With .70-.85%. I have never seen steel with 35% carbon. That would be nasty and not make very good knives . Might as well use a chunk of coal.

 

Edited by Vern Wimmer

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Forgot the decimal :p, but youre somewhat wrong on that because 1045 is very quenchable to the same rhc 60 standard everyone adores.

Edited by Joe Wulvz

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Good hardening and making a good knife takes a bit more carbon. I don't know anyone who sets out to use it solely to make a blade. It will weld up with a higher carbon steel for pattern welding to develop a pattern if other conditions are met and may make  another tool but as a stand alone for a knife...mneh. 

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Historically speaking swords were hardened to Rhc 40-55, we only use 60 as a standard because a air hardening stainless steel air quenches to rhc 60. its the derp method to say that your newer steel is better then a junk stainless knife for kitchen purposes. also if you took your rhc 60 sword in a time machine it would break and you would die from not having a sword. The more you know :P

Hardenability in carbon however the change is about .35% where it starts to harden, but your quenching temp is different. and were talking about water quenching here not oil. 

Edited by Joe Wulvz

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