Damascus etching problem

O

oldwolf

Joined
Dec 29, 2002
Messages
617
Iv'e etched damascus previously and had no problem, but this one has me stumped. The billet came etched and looked very even. After the blade was ground, heat treated and tempered I etched it in a 4 to1 solution of water and FC for a total of 5 minutes. The etch from the beginning of the ricasso to the tip came out great, just like the etch when I received it. However the last inch before the guard looks flat and kind of greyish depending on the light angle. I resanded it all down to 320 grit and redid the etch and it comes out the same way. The only thing difference I know is that that area did not get ground on the belt grinder as most of the blade did. It was nice and flat and needed nothing. What's going on here?:confused:
 
A few thoughts:

- Did you clean the entire blade with acetone prior to etching? If there are any oils, etc on the surface it can affect the etch.
- Did you differentially heat treat the blade? If you left a section not hardened it may look different (usually the dark won't be as dark) due to a lack of martensite in that part of the blade.
- Are you certain that the etchant was evenly mixed? Stir it up and make certain that the mix is even.

Unless you were REALLY grinding hot, the grinding shouldn't have caused any structural difference in the steel. If the things above aren't it, describe in detail your etching procedure and maybe we can come up with some more ideas.

-d
 
Everything Rob said, especially the part about the ricasso being a different structure. If it was edge quenched, and the ricasso didn't go in soon enough, it could be mostly pearlite, or a mix of pearlitre austenite and martensite. It will etch very differently than the martensitic blade.
Stacy
 
Ok, I think it might be that the ricasso area did not get hot enough. When heat treating I don't usually worry about anything but the blade being hardened. Looks like with Damascus I need to treat everything that shows the same. Back to heat treat it again.
 
I agree, there are really only two things it could be, given the effects you describe. Either that section isn't martensite(which means it didn't get HT properly), or its surface decarb.
I would reheat treat it and make sure you back up to 220 grit on the machine and then go with your normal grit progression from there.
Thanks,
Del
 
Thanks Guys for the help. I did the heat treat again making sure I got everything up to critical. This time the etch came out fine.
 
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