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Thread: N690 rusting

  1. #51
    member MadRookie's Avatar
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    Aah, ok.....



  2. #52
    It is always great to see someone taking the interest and really want to get to the bottom of things. Good on Andreas and on Bohler.

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    Last edited by marthinus; 05-16-2014 at 07:16 AM.
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  3. #53
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    Just a thought... ?

    This might have been a mis-match in steel type by the suppliers, and I suggest that this might be D2...

    And it is based on my own experience...I bought two lengths of N690 years ago in RSA, and when I ground them, they felt different...harder and "stickier"...
    The sparking was different as well...

    I went back to the suppliers, Bohler in New Germany, and found out that it actually was D2...
    I kept it and used it for other projects, but bought more (actual ) N690...
    Everyone was happy...

    I am watching this space...
    Last edited by Zackerty; 05-16-2014 at 01:29 AM.

  4. #54
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    Me too !
    You'll probably blame us metallurgists but we didn't do it ,that guy over there did it !!
    At least you're learning something.

  5. #55
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    Quote Originally Posted by Pieter View Post
    Here is the problem !!!

    Got the knife today and it looks Bad. I have no idea why this has happened but it does not look good. I am planning to take the knife to Bohler and hear what they suggest

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    I do not post here often, but here's my humble contribution:
    This type of rust looks EXACTLY like the rust that forms on knives that has been washed in a dishwasher. I know this from personal experience since some of my relatives wash their knives in the dishwasher exclusively. My brother used to work in a restaurant, and they washed their knives in their industrial dishwasher, came out looking like this.
    The same type of rust can be seen on some of the knives Martin Bergander (a knife dealer in Bielefeld, Germany) has used in his experiements to find the least aggressive detergent for dishwashers.
    The knife blade you taped up? It could be galvanic corrosion, or it could be sweat/contaminants from your fingers trapped under the tape, given that it is hot in SA ( I presume? ) all chemical reaction will occur faster, including the oxidation of your steel, if exposed to corrosive agents. Try rubbing a sweaty finger on a piece of Stain-resistant steel and then cover it in masking tape and leave it to "cook".
    The batches bohler makes their steel in are so large, that the chance of just a few centimetres of stock is bad is very unlikely, let's hope that other knifemakers will chime in, if they have had similar experiences with n690?

  6. #56
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    Finger prints ?? A bit OT but working in a bearing factory I had an interesting helicopter bearing as a desk ornament. Blued [ like a gun ]and dippped in rust preventing oil ,one morning I came in and found a perfect set of fingerprints in rust !!! I soon found the guy who did it. Oh that was me , he said ! He had the problem of acid oils in his skin ! There are special soaps and lotions for those people. This was a bearing steel not stainless.

  7. #57
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    Any follow ups on this subject?

  8. #58
    member Pieter's Avatar
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    I am still waiting on official confirmation but. Bohler Cape town sent the blade to Joburg for testing. The test showed that there was a problem with the steel and Bohler have since then sent the blade to Austria for further analysis. Have not heard anything else yet but will keep you updated when I do get more news

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