Strange pattern on 8670 steel after ferric chloride etch?

T

Tyler.t76

Joined
May 19, 2022
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I’m working on a knife, made with 8670 steel from PKS, and I etched in ferric chloride as I’ve done many times before, and it came out with a very interesting super tight pattern similar to Damascus. The was hardened the same way I harden all my 8670, and the flats were sanded to 400, and the bevel was taken up to a 1000 grit trizact and then run on a cork belt for a semi mirror finish because I was curious how it would look with the etch. So, anyone have any clue what caused this pattern? Is it possibly a bad sign? I don’t know how to upload images here, so if someone needs to see a photo please let me know how I can get them to you.
 
I (we?) would like to see pics.

I would suspect you may have other steels mixed with your 8670, or perhaps your FeCl3 is contaminated.

You need a pic hosting site. Imgur is good and free. Upload your pics there, select your pic and click the box for "message boards and forums". Paste that link here.
 
I would suspect that your 8670 may have some stainless steel (or higher chromium content carbon steel) contaminants in it. It doesn't look like it should affect anything, assuming your heat treatment went ok. And as a bonus, you got a damascus-look without even trying. Dip it a few more times and see if it brings out the pattern even more. :)
 
shane45-1911 said:
I would suspect that your 8670 may have some stainless steel (or higher chromium content carbon steel) contaminants in it. It doesn't look like it should affect anything, assuming your heat treatment went ok. And as a bonus, you got a damascus-look without even trying. Dip it a few more times and see if it brings out the pattern even more. :)
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Thanks, I figured it wouldn’t be too much of an issue, and unfortunately my customer was dead set on a stone wash look on this blade, even after I showed him the pattern, so it isn’t as clear but is still pretty noticeable in the right light. I’m going to try to replicate it on my next blade I make from that bar of steel though definitely!
 
shane45-1911 said:
Welcome to the forum, BTW.

I'd like to see finished pics of this knife when you're done. :)
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Thank you, and I’m not sure how much I’ll post here other than questions(I’ve only been truly doing this for less than a year and I’ve got a lot to learn), and it will definitely be posted there in a couple days once it’s finished!
 
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Micro-scratches responding to the etchant? Maybe a phenomenon similar to 'orange-peeling' when finishing some steels? Not a clue......
 
That looks similar to carbide banding, which is why wootz looks that way it does. There is segregation of elements as the steel solidifies during casting. This segregation is elongated during rolling the steel into plate/sheet. The bright areas are probably enriched in Cr or Ni.
 
H0kieengineer said:
That looks similar to carbide banding, which is why wootz looks that way it does. There is segregation of elements as the steel solidifies during casting. This segregation is elongated during rolling the steel into plate/sheet. The bright areas are probably enriched in Cr or Ni.
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That makes sense, would this be a negative in any way?
 
H0kieengineer said:
That looks similar to carbide banding, which is why wootz looks that way it does. There is segregation of elements as the steel solidifies during casting. This segregation is elongated during rolling the steel into plate/sheet. The bright areas are probably enriched in Cr or Ni.
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that's what I was thinking, I get that with the A2 I use
 
Yep, looks very much like carbide banding. Interesting, as the 8670 I have used from Alpha Knife Supply didn't have banding at all.
 
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