Case hardening?
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    Case hardening?

    There are several kinds of case hardening. In very simple terms it is adding a hardened skin to a soft low carbon steel.

    Case-hardening involves packing the low-carbon iron within a substance high in carbon, then heating this pack to encourage carbon migration into the surface of the iron. This forms a thin surface layer of higher carbon steel, with the carbon content gradually decreasing deeper from the surface. The resulting product combines much of the toughness of a low-carbon steel core, with the hardness and wear resistance of the outer high-carbon steel.

    Colt uses a traditional method far as I know but they do change things around a lot so who really knows? I have begun to wonder when you see the distinct change in colors on Colts' work. You can see every thing from the more obvious traditional work of Doug Turnbull to stuff that could easily be just another case hardening process ( salt bath? ) that was used.


    a well used Colt from 1973





    Colt has traditionally used this method:

    The traditional method of applying the carbon to the surface of the iron involved packing the iron in a mixture of ground boneand charcoalor 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.


    The resulting case-hardened part may show distinct surface discoloration, if the carbon material is mixed organic matter as described above. The steel darkens significantly, and shows a mottled pattern of black, blue, and purple caused by the various compounds formed from impurities in the bone and charcoal. This oxide surface works similarly to bluing, providing a degree of corrosion resistance, as well as an attractive finish. Case colouring refers to this pattern and is commonly encountered as a decorative finish on firearms.Case-hardened steel combines extreme hardness and extreme toughness, something which is not readily matched by homogeneous alloys since hard steel alone tends to be brittle.

    A used, but newer Cimarron. Uberti uses a true case hardening, salt bath, process described below. I've long seen the salt bath process described as a "chemical process".....implying it is not a case hardening which is not only misleading but untrue. In fact the salt bath gives a harder outer skin than bone and meal case does, just not the bright colors. When you look further there actually might be some advantages to the shooter and manufacturing costs to the salt bath over the bone and meal version.




    Another process
    that is used on the SAA guns is a "salt bath". After seeing the process being done and the end result close up on more than a dozen guns I began to wonder and do some research.

    This process is clearly seen in the Uberti video at 2:20

    https://www.bing.com/videos/search?q...345C&FORM=VIRE

    Cyaniding ( salt bath of sodium cyanide ) is a case-hardening process that is fast and efficient; it is mainly used on low-carbon steels. The part is heated to 871-954 °C (1600-1750 °F) in a bath of sodium cyanide and then is quenched and rinsed, in water or oil, to remove any residual cyanide.
    This process produces a thin, hard shell (between 0.25 - 0.75 mm, 0.01 and 0.03 inches) that is harder than the one produced by carburizing, and can be completed in 20 to 30 minutes compared to several hours so the parts have less opportunity to become distorted. (which answers a few more questions for me on "consistent production".)



    Then there is Ruger's version that is now discontinued and I don't believe was ever a hardening process but only cosmetic.



    (photos came from the Ruger forum without the author's permission)

    I'm lookin for information on how these processes compare in actual use. Please feel free to add your thoughts and knowledge to the conversation.
    Last edited by Cozmo; 08-26-2018 at 01:47 PM.

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    It's my understanding color case hardening hasn't been needed on Colt SAA at least on 2nd and 3rd gen Colt's but is done just for tradition. The Uberti's are just a step above Ruger's faux CCH. DSCN0619.JPGColt SAA from 1966, a shelter life for the most part I guess. The Color Case still looks good, the old charcoal and bone method.
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    >my understanding color case hardening hasn't been needed on Colt SAA at least on 2nd and 3rd gen Colt's

    true

    >The Uberti's are just a step above Ruger's faux CCH

    Not even close when you look at the process used. Colors and cosmetics might not be what you like but the hot salt process is likely better than Turnbull's bone and meal for getting what it required from a hardening standpoint.

    I get the cosmetics and why folks like bone and meal cased colors. But to my surprise bone and meal is not the only "real" case hardening techniques.


    I've seen "bone and meal" case called "real case hardening" many, many times. When in fact that isn't even remotely true. It might be the oldest process and no question it can be really pretty. But that isn't the point. The real point is, it is either case hardened, or it isn't.
    Last edited by Cozmo; 08-26-2018 at 01:57 PM.

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    Bone and charcoal give the overall best results, and durability. Cyanide Hardening works too, longer it stays in the bath the deeper the Hardening goes up to a point. However cyanide hardening will never produce the colors or durability of bone and charcoal. Cyanide coloring tends to wear off and fade fast. Regular case Hardening will gradually fade too, but it takes longer. Plus cyanide is downright dangerous.

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    >Bone and charcoal give the overall best results, and durability.

    By what standards are you making that claim?

    >cyanide hardening will never produce the colors

    agreed by what we have seen to date

    >or durability of bone and charcoal. Cyanide coloring tends to wear off and fade fast.

    again by what standard are you judging that by? I have not found that to be accuarate

    > Regular case Hardening will gradually fade too, but it takes longer.

    Takes longer I suspect because there are a whole lot of Colts that simple don't get used, shot, cleaned.
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    Doug Turnbull



    USFA Artillery repro



    Colt 1957
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    Cyanide colors can be beautiful and were traditionally used on guns like the Sharps rifles but IMHO, it doesn't belong on a single action.

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    I base my opinion on use. Sharps rifle company, the original used bone and charcoal. Several companies that make newer copies of old single shot rifles use the cyanide method and can get some decent colors but it fades. The ripple effect is caused by how they raise the parts out if the cyanide bath, and then the quenching. Cyanide Hardening is also used to heat treat gears or some use induction Hardening.
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    Thanks guys.

    Mike, I wasn't trying to be a dick just trying to ask questions. Like Craig we all have opinions. Me as well My interest is in the process. Salt bath is half as deep on the metal and it is harder, than bone and meal. For guns made of modern steel that don't need hardening one might wonder which process is actually better on a SAA, if you can disregard the colors. Easy to see which is cheaper. But we also have a 100+ years of additional knowledge and technology to come up with better ideas.

    My guns end up with faded blue and no matter who did the color case process generally white...be it Turnbull or older Colts. I've not found the current Uberti salt process fragile at all....quite the opposite actually.

    Along the lines of with better technology? The hot salt bath has less chance of warping a frame. Warped frames are the typical cause of a SAA not shooting POA/POI when the barrel threads get tweaked so do the barrels. And you no longer have a square gun. Square gun is the key to a fixed sighted hand gun shooting where it is suppose to.

    With a dozen new Ubertis here and all shooting like they should and knowing from experience there no way in hell would you ever get a dozen Colts in house from a few months production that would shoot as well one might....just might... want to start asking why the Colt QC is so bad. I have to wonder if the after market jobber's bone and meal case coloring isn't one of the issues.....warping frames.
    Last edited by Cozmo; 08-26-2018 at 03:11 PM.

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    I forgot to add that my experience is based on years of collecting single shot rifles such as Maynard Sharps, rolling blocks and others. And some of these were junkets that were restored but I learned early on that the Traditional method always look the best and wear better. My 1906 Bisley that survived the San Francisco earthquake is faded on the outside, but pull off the trigger guard and you can see the beautiful colors. Each smith that does color case work kinda gaurds the exact formula that they use, one for Colts is different than what they would use for a Winchesters. Some of the least expensive Smith's have the best results. I particularly do not like color case from Turnbull, but that's me. Others like him. I enclosed a picture of my Bisley . I have a Ballard loop lever that still has good color case after years of use.
    Attached Images Attached Images


 
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