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  1. #1
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    Default Chisels Breaking

    Not sure if this is the right place to put this.I don't know if I have done something silly but would like to know what has happened.
    Last night I placed 5 Berg chisels in a jar with some white vinegar to clean some gunk off them.When i went to clean them up this morning 2 of them snapped like chalk about 1 inch from the tip.Wasn't to happy to say the least.The other 3 were fine.

    cheers ,,,,,Roy

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  3. #2
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    Vinegar didn't cause them to break. They must have had preexisting defects.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  4. #3
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    They are obviously junk but I'll take them off your hands.

  5. #4
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    Quote Originally Posted by rob streeper View Post
    Vinegar didn't cause them to break. They must have had preexisting defects.
    Except vinegar does cause a exothermic reaction in steel which is why you should never use it,

  6. #5
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    Quote Originally Posted by 44Ronin View Post
    Except vinegar does cause a exothermic reaction in steel which is why you should never use it,
    True but inconsequential. To begin softening hardened carbon steel the temperature must be well above the boiling point of water.

    These plots give the hardness and annealing temperatures of 1095 and 1074 plain carbon steels. These correspond to steel having ~.95% C (hypereutectic) and ~.74% C (eutectic) levels of carbon. These levels correspond to the ranges required to produce chisel hardnesses in the typical range of around HRC60.

    I have been doing a study of chisels and recently looked at Berg chisels (Chisel Hardness Study, the first step. @#95). Bergs are poor for edge retention in my testing.

    To appreciably lower the hardness of a Berg chisel, measured at HRC ~59.5, the temperature of the vinegar would need to be > 419 oF for 1074 steel and > 460 oF for 1095 steel, well above the boiling point of water at 1 atm. The energy input from overnight soaking in vinegar is likewise far too low to fracture a workpiece having a tensile strength > 100ksi. Likewise, hydrogen embrittlement is a non issue because the temperature needs to be about 30% of the melting temperature for it to become a factor.

    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  7. #6
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    Quote Originally Posted by Chris Parks View Post
    They are obviously junk but I'll take them off your hands.
    I will get back to you about that one Chris

  8. #7
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    Thank you Ronin and Rob. I was worried that there was some sort of chemical reaction going on but was puzzled to why.

    Rob your suggestion of a previous crack may be on the money as these are second hand chisels and I have no idea what sort of life they have lived.If there was a hairline fracture it's possible that the vinegar could of penetrated and done the damage ? Also the metal was a grey colour and looked chalky but there didn't appear to be evidence of a darker area to indicate any metal fatigue.The chisels were a 1/8th and a 1/4 so fairly hard to see as they are so thin.

    It's interesting to hear your view on the Bergs as I like them and feel that they aren't to bad.Maybe I can sell them to Chris at an inflated price before he reads this post.Interestingly there is a seller on ebay selling old Bergs saying all you need to do is give them a sharpen and you have a $1000 set of chisels.
    If vinegar is not good what would you recommend to remove the rubbish from old chisels ?

    cheers.....Roy

  9. #8
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    Some pictures of the broken chisels might help.

    Citric or oxalic acids work fine. You can find citric acid in the canning supplies area of your grocery and oxalic acid is sold as wood bleach. Phosphoric acid also works well, check eBay.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  10. #9
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    Roy,

    Vinegar is an exceedingly good glue remover. 99.99% chance someone broke them, glued them back together, and sold them .. Probably the "patina" hid the evidence of glue...

    Quote Originally Posted by royflatmate View Post
    Not sure if this is the right place to put this.I don't know if I have done something silly but would like to know what has happened.
    Last night I placed 5 Berg chisels in a jar with some white vinegar to clean some gunk off them.When i went to clean them up this morning 2 of them snapped like chalk about 1 inch from the tip.Wasn't to happy to say the least.The other 3 were fine.

    cheers ,,,,,Roy

  11. #10
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    Quote Originally Posted by rob streeper View Post
    True but inconsequential.
    Consequential.

    Acetic acid found in vinegar accelerates rust. If there's residual water in the jar, its even worse.

    Don't do it.

  12. #11
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    Quote Originally Posted by 44Ronin View Post
    Consequential.

    Acetic acid found in vinegar accelerates rust. If there's residual water in the jar, its even worse.

    Don't do it.
    The complaint was breaking, not rusting.

    Cleaning in dilute solutions of weak organic acids for short periods of time will not damage the chisels. If acid treatment were detrimental to steels pickling would not be used in the industrial production of steel. https://en.wikipedia.org/wiki/Pickling_(metal)
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  13. #12
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    Agree with rob, both were already faulted before cleaning. I mentioned in this thread or another one, George Wilson snapping the end off of a marples chisel. He suspected the same - a fault.

    I have done the same with another chisel - I believe it was greenlee or rockford forge or one of the illinois makers. I could see a tiny hairline in the metal and it eventually broke. No other sign of abuse on the chisel - presume it was a steel issue.

  14. #13
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    Quote Originally Posted by rob streeper View Post
    The complaint was breaking, not rusting.

    Cleaning in dilute solutions of weak organic acids for short periods of time will not damage the chisels. If acid treatment were detrimental to steels pickling would not be used in the industrial production of steel. https://en.wikipedia.org/wiki/Pickling_(metal)
    From the very article you posted..

    "hydrogen from the acid reacts with the surface and makes it brittle and causes cracks"

    eg.
    http://events.nace.org/library/corrosion/Forms/embrittlement.asp

  15. #14
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    Quote Originally Posted by 44Ronin View Post
    From the very article you posted..

    "hydrogen from the acid reacts with the surface and makes it brittle and causes cracks"

    eg.
    http://events.nace.org/library/corrosion/Forms/embrittlement.asp
    And the very next sentence: "Because of its high reactance to treatable steels, acid concentrations and solution temperatures must be kept under control to assure desired pickling rates."

    Acetic acid is a weak acid with a Ka of 1.75 X 10-5 at room temperature. The low Ka is why you can put vinegar on your salad and it won't dissolve your teeth or burn your mouth. The acids used in pickling are strong acids and thus provide much more ionic hydrogen to induce embrittlement.

    Hydrogen diffusion into metals becomes a significant factor at temperatures ~30% of the solidus which, for steel is something in the range of 400 oC depending on the alloy. The temperature of the treatment of the chisels described above is not high enough. Any hydrogen absorbed diffuses back out.

    As a practical matter hydrogen embrittlement is typically a concern in applications where high temperatures, lots of hydrogen and high stresses are encountered, applications like jet engines and power plants.

    Another example of utility here is steel ships, particularly warships. These vessels are often manufactured using high strength heat treated steels. They're exposed to a lot of hydrogen and hydrogen containing molecules in the form of water. They're also exposed to salts which are corrosive and chloride which is also known to induce corrosive cracking in various alloys. Yet despite all of these seemingly scary deleterious exposures we don't read of battleships and aircraft carriers shattering due to hydrogen embrittlement.

    BTW, your first response above advocated the importance of the 'exothermic' nature of the interaction of vinegar and steel.
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

  16. #15
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    This article (JOM Article on The Titanic: Did a Metallurgical Failure Cause a Night to Remember?) raises an interesting possibility, what if the steel used in the Berg chisels was inherently brittle due to high sulfur content?

    According to the attached later paper the sulfur content of the Titanic at least wasn't the issue. A number of factors combined precipitated the failures and overall it was simply that the steel made 100 years ago isn't as good as the stuff we have now.

    The author comments that metallurgical techniques were only just being developed and that the engineers of the time were doing the best they could given their ignorance of a number of important factors.

    Testing is important.

    Metallurgical analysis of the steels of the Titanic RS highlights.pdf
    Innovations are those useful things that, by dint of chance, manage to survive the stupidity and destructive tendencies inherent in human nature.

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