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  1. #16
    BobL is offline Member: Blue and white apron brigade
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    Quote Originally Posted by onanonanon View Post
    Nice googling, but. it's about the carbon content of the steel in relation to quenching and running colours. Car springs make excellent knives, car axles don't as the carbon content is relatively low by comparison, they do make good hammers though. Aside from oil and salt water, lemons and lemon juice were also a quenching solution.
    No googling, The info comes from a set of 50 year old metal working books that an old techie gave me at work about 10 years ago, and the documents and notes from a blacksmith course I attended 5 years ago.

    Whether a steel is oil, air or water quenched doesn't have much to do with carbon content.
    WI and O1 are water and oil quenching steels respectively, and have very similar carbon contents.
    A2 (similar Carbon content to both W1 and O1) and is preferably air quenched.
    M2 has the narrowest range of Carbon content that is inside the ranges for W1, O1 and A2, and can be brine, oil or air quenched.

    Hardening to depth (case hardening) has been done since Roman times.
    The method you refer to above about wrapping metal in hair and bone to infuse C into metal only works for a shallow depth is an example. Teh Carbon from the padding materials does not penetrate far thick pieces of steel no matter how long you leave it.

    Since medieval times serious blacksmiths developed special case hardening powders and these are widely available - you might like to try google to see how widely available they are?
    One of the members on these forums has been selling this stuff and was giving away small samples at one of the scraping class meets in 2014?

  2. #17
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    Quote Originally Posted by BobL View Post
    No googling, The info comes from a set of 50 year old metal working books that an old techie gave me at work about 10 years ago, and the documents and notes from a blacksmith course I attended 5 years ago.

    Whether a steel is oil, air or water quenched doesn't have much to do with carbon content.
    WI and O1 are water and oil quenching steels respectively, and have very similar carbon contents.
    A2 (similar Carbon content to both W1 and O1) and is preferably air quenched.
    M2 has the narrowest range of Carbon content that is inside the ranges for W1, O1 and A2, and can be brine, oil or air quenched.

    Whether a metal is quenched in oil, water, lemon juice, blood or salt water, the carbon content dictates how how hard or brittle the metal will be after quenching. The quenching medium is best selected by how much carbon is in the metal. Some metals can be quenched in water without any ill effects and can then be tempered. Other metals, obviously with higher carbon content, will shatter.

    Hardening to depth (case hardening) has been done since Roman times.
    The method you refer to above about wrapping metal in hair and bone to infuse C into metal only works for a shallow depth is an example. Teh Carbon from the padding materials does not penetrate far thick pieces of steel no matter how long you leave it.

    I never said it penetrated the full thickness. Still, carbon will penetrate further into metal if left for days in a furnace that a piece left for 5 minutes = common sense. Testing of medieval weapons does indeed reveal to what the depth carbon penetrates. Many tools from medieval times, if sharpened or ground enough will eventually reach the depth to which carbon has penetrated. They had a term for that in the medieval ages. I'm sure googling will bring it up. Many medieval tools that have been found were discards as the continual sharpening and grinding took their toll and the tool past the carbon infusion layer. Many medieval tools were made in a similar fashion to samurai swords, ie, a softer steel formed the core and a high carbon steel was welded to the exterior. this had basically the same effect as carbon infusion in a furnace as eventually constant sharpening and grinding would wear away the carbon steel coat revealing the softer inner cor. This was a popular method simply because good carbon steel was not plentiful, difficult and time consuming to make and had the same end result.

    Since medieval times serious blacksmiths developed special case hardening powders and these are widely available - you might like to try google to see how widely available they are?
    One of the members on these forums has been selling this stuff and was giving away small samples at one of the scraping class meets in 2014?
    Case hardening? Who the devil is talking about case hardening, certainly not me. Case hardening would have worked real well on swords wouldn't it? Case hardening is not hardening to depth, totally different processes. Case hardening is as its name suggests adding a layer of hard material. Carbon infusion is also as it suggests, carbon is infused into the metal.

    I google all the time, but mostly I know what I know not from reading books or googling but from actual experience. W1, W2, etc,means beans to me.

    Some useless info: Old samurai swords were made by wrapping carbon steel around a softer steel this is what gave the swords their fine edges and toughness. I have read that today's swordsmiths have difficulty in replicating these swords.

    More useless info: Damascus steel was made by heating very low carbon steel, sprinkling it with very small pieces of high carbon steel, folding and beating over and over. This is what gives Damascus steel it's pattern or what looks like grain. It was said that a Damascus steel sword could be bent in a circle so tip touched pommel and when released would spring back to it's original shape - straight. Whoever was able to bend a sword like that would certainly put Arny to shame! Damascus steel knives are available on ebay should anyone wish to try them.

    I'm sure someone will feel the need to add corrections with dates, percentages, etc. Just more useless information, but entertaining nevertheless!

  3. #18
    BobL is offline Member: Blue and white apron brigade
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    . . . W1, W2, etc,means beans to me.
    You could always try googling it?

  4. #19
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    Quote Originally Posted by onanonanon View Post
    Case hardening? Who the devil is talking about case hardening, certainly not me. Case hardening would have worked real well on swords wouldn't it? Case hardening is not hardening to depth, totally different processes. Case hardening is as its name suggests adding a layer of hard material. Carbon infusion is also as it suggests, carbon is infused into the metal.
    I'm with BobL on this one Onanonanon, you may not have mentioned the term "case hardening", but you have certainly mentioned the process. Case hardening refers to a process not where an extra layer of hard material is added, but a thin outer layer has carbon infused into it making it a higher carbon steel, and so capable of being hardened by quenching into some quenching medium, be it water, brine, oil, air or any other suitable quenching medium. The process you spoke of using hair and bone fragments wrapped around the workpiece and heated in the relative absence of oxygen, followed by quenching, is one process which will case harden suitable steels, but I have no knowledge of it being suitable or otherwise for the manufacture of sword blades. I would think that if there was a suitable steel for case hardening, which was tough, like a spring steel for instance, it could work, but there may be difficulties obtaining a suitably tough springy steel which could still be case hardened, I simply don't know.

  5. #20
    BobL is offline Member: Blue and white apron brigade
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    Cheers RT.

    Modern case hardening is indeed usually just a very shallow process but look up the Wikipedia entry for "Case hardening", under the "historical section of case hardening" it states;

    The traditional method of applying the carbon to the surface of the iron involved packing the iron in a mixture of ground bone and charcoal or a combination of leather, hooves, salt and urine, all inside a well-sealed box. This carburizing package is then heated to a high temperature but still under the melting point of the iron and left at that temperature for a length of time. The longer the package is held at the high temperature, the deeper the carbon will diffuse into the surface. Different depths of hardening are desirable for different purposes: sharp tools need deep hardening to allow grinding and resharpening without exposing the soft core, while machine parts like gears might need only shallow hardening for increased wear resistance.
    Modern case hardening is indeed mainly a shallow process used in fewer situations than in the past because deep hardening takes too long and because many more specific alloys are available to meet similar needs rather than trying to meet those needs with traditional l time consuming deep hardening methods.

    There were many other methods to obtain the optimum spatially desirable hardness and other properties for swords .
    Look up Wikipedia for "Differential heat treatment"

  6. #21
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    Quote Originally Posted by BobL View Post
    ........................
    One of the members on these forums has been selling this stuff and was giving away small samples at one of the scraping class meets in 2014?
    Gratuitous self promotion here, thanks to BobL for providing a segue. Cherry Red case hardening powder is still available and also the PBC anti-scaling compound. I usually have it going around on eBay but its a little cheaper if you contact me directly as I'm not up for eBay and PayPal fees.

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