hardening steel
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Thread: hardening steel

  1. #1
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    hardening steel

    I made a knife out of old file.
    Last night i tried to harden the steel. Made sure the magnet wasn't attaching to steel before cooling. First I tried to cool it in oil. It wasn't hard enought. Second i used water, same thing.
    Not sure why but it's still not hard. I used an other file and i can take metal out.

    Any one can help out, what am i doing wrong?

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    pics / vid required for validation

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    looks like I got a bad piece of steel 8(
    And I was hoping that I didn't do something right.

    too bad 8(
    http://www.theoutdoorstrader.com/att...299580&thumb=1

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    Did you anneal the file before trying to work on it? At this point you have at least two thermal cycles on the file blade. Some hardening oils will work for file steels (usually W1 or W2) but you need to choose the right ones. What brand of file was it?

    Does a file skip over the entire edge or just parts of it? How did you heat the blade? how did you dip it in the quench (vertically or flat)? Did you heat the quench medium prior to quenching?

    There are many variables at play. Part of being a good knifemaker is narrowing down the variables to maximize your chances of making a good quality blade.

  6. #5
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    Yes, it was annealed.

    It was hard to read markings on the file. What I made out was "Superior". I wasn't able to find that company. It was just cheap piece of steel that I got at a flea market. I wanted to try to make a knife for some time. So found a piece to try on. I guess ti was a gamble, since I didn't know what steel it was.

    Yeah, that's how I tested for hardness. I used an other file and it doesn't skip.
    It was heated on a home made forge.
    It was vertically with me swerving the blade.
    Medium was at outside temp.

    What i been told locally is that I didn't normalize the steel between hardening.

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    I've never tried making a knife out of a file. Their limited sizes was probably what deterred me.

    It is possible that the quality of steel is so bad that it will never make a good knife. But i'm inclined to think that if it was a file once, it was hardened to work as a file. Therefore, it should harden again. I would reexamine your hardening process. Make sure you are getting sufficient soak time in the forge. I would also try a quick quenching oil instead of water and make sure it is heated to the recommended temp. Heating the oil keeps it from forming as much of a steam sheath around the blade that acts as an insulator when you quench it. Moving it like you said should also help.

    Normalizing is a stress relieving process so I don't see how that could make much difference with hardening.

    Keep trying and you'll get it. It's a learning process that can be very frustrating but when you finish a knife it's fulfilling.

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    It has been 25 years since I did anything with my Metallurgy degree, but lets see if I can help. Is there a part of the knife you do not mind doing a little grinding on? There is a quick & dirty method of learning something of the composition of a piece of steel called spark testing. IIRC, Wikipedia has an article on it. Before you do anything else, do that, if you can.

    There is one way to give it a more severe quench than water, and that is brine. Salt in the water makes the little bubbles that form on quenching collapse faster, resulting in faster heat transfer. I remember nothing about how much salt per unit of water.

    If you are not getting any hardening response from water quenching after Austenitizing, the chances are that you have a non-hardening grade of steel.

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    " spark testing" very interesting. I'm going to try that.

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    NuJudge

    I done the spark test. Looks like I might have a mild steel. 8(
    It was long sparks.



    Looks like I'll just leave the blade as is right now. It will be wall piece and a good lesson for me.
    All your comments are very helpful and i have learned a lot.
    thank you.

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    The only thing wrong with a soft steel knife is that you will have to sharpen it a lot. My favorite 1930's vintage Marbles hunting knife seems pretty soft, in that it seems to dull quickly, but even so, I once field dressed 5 deer with it. Boy, was it dull after that.

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    The newer Chinese made files use mild steel with some kind of cyanide case hardening compound process applied, once annealed they are just a chunk of mild steel. You need an older american file, even newer american files like diamond are doing this now. Its cheaper but still makes a usable file out of mild steel like 1018.

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    can anyone tell me about any other testing instead of spark testing?

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    Rockwell hardness testing, a well equipped machine shop should have one, the spark test really does work. One of the things I would do when I first started making knives, to test and see if my hardening process was working was to take the knife, place it in a vise, right before I hardened it and run a new or very good file across the edge with medium pressure. Take note of the "feel" and "sound" of the file moving across the steel, it should have a low coarse grinding tone and the file should "dig in" offer some resistance and noticeably remove metal, you can feel it and hear it. After heating and quenching the blade I would repeat the test, if the hardening process was successful the sound will be completely different, a higher pitch, and the blade should "sing" with the vibrations. The feel should be remarkably different, the file should "skate" across the blade as if the file was incredibly dull and there should be little if any metal removed.

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    Torx: I do believe that type56-1 is correct, you probably had a file made of mild steel that was chemically case hardened, you will not be able to heat treat the blade. When I make blades from files I like to use Nicholson "black diamond" brand files, I usually pick them up from flea markets or garage sales. Make sure they are older ones, they are made from W1 or W2 steel and make excellent blades. If you ever want to do a Japanese style heat treat using clay to achieve a visible hamon or temperline W series steel will give a beautiful hamon.

 

 

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