Crystals appearing in Damascus?!?

J

JosephSchultz511

Joined
Jun 22, 2022
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For some reason, a knife I made looks like a geode after etching in ferric chloride. Does anyone know why? It’s only in the 1080, it looks like when you snap a file and see the grain structure, so the 15N20 layers look normal, then the recessed 1080 layers have spots that look like crystal pockets
 
I’ve seen it happen with ferric chloride diluted with hard water.

I’ve also seen it happen with older FC that’s been used on several different types of steel alloys.

It could be grain structure, not sure. A pic would help.

Hoss
 
Large grain structure can etch in a geometric looking pattern. In making the damascus, the simple carbon steel goes through repeated high temperature cycles and long soaks. This can make huge grain structure. Doing grain refinement cycles while normalizing after forging out the damascus usually solves this.
 
I forged it out at roughly 1600 to 1700F, then did a normalizing cycle at 1600F, then did thermocycles starting at 1550F going down by 50 degrees each cycle and doing the last cycle at 1350F. I've done this same heat treatment for all my blades and broken some test blades after it and had a really fine grain structure. The crystal looking pattern that appeared during the etch looked about like 1000 grit sandpaper. It only appeared in a couple of places on the blade.
 
Mayb some sort of carbide separation? Do they get more distinct as you sand/polish them?
 
They smoothed out with sanding, but I did a deep etch to try to get a good layer of oxides on the 1080 and the crystal pattern showed up in the same few spots.
 
Does it look like some of the photos in Larrin's book ... or a meteorite that has been etched to show the Widmanstätten pattern?
 
It doesn't resemble meteorite, it resembles the fine grain structure that you see when you break a blade, it's not course, it has a frosty look, like not a matte finish like you'd expect for an etch, and if you look closely it looks like a fine powdery sand, resembling a fine sandpaper.
 
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