Carbon flake

J

Jefflynn

Joined
Feb 19, 2017
Messages
52
On 1095 I get black flakes in my blades. And noticed it in many 1095. But my 1084 is clean. No black flake or spots. Does anyone experience this. If not, why does 1084 stay clean.
 
Without a photo we don't understand what you are calling a flake. Please posy a few good close-ups and one of the whole blade.

Here are some questions that will help:

Are you forging this steel?
Is it on the steel when you get it, after forging it, or after HT?
When you say "flake", does it fall off?
Where did the steel come from?
What was the surface of the steel when purchased (cold rolled, CRA, precision ground, etc.)?
 
I need someone to take the the time; tell me how to post a pic. Ive, only HT.1084. I bought blanks of 1095 and all of them have carbon spots. On the finished blank. And i bought blanks from 2 diferent bladesmith. When I buy blanks of same bladesmith In. 1084, that are always clean. I do stock removal, and use a crude coal forge, and all my 1084 are clean. No it doesn't flake off. It's there permanent.
 
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Blanks that have it came from Miles martin Alaska. And he does great work. Other came from Texas knifemaker. But i buy Aldos 1084, and it is his own specs. Not exactly like ANSI.
 
To post a picture, go to a site like Photobucket or Imgur and upload the picture. You don't need an account, but if you want to do this often setting up an account makes the most sense. When it's uploaded, you'll be given a shareable link that looks like this:

Code: 
[img]//thelinktoyourpicture.com/nameofpicture[/img]

And you copy and paste that here in a post.
 
Do the spots go away after you grind the steel?


If the blanks are just flat knife profiles, what you are seeing is most likely the surface scale from the mill finish on the bars/sheets he cuts them from.

Most of Aldo's steel has had the surface cleaned up to some degree. The steel from the chap in AK probably probably has a mill finish surface, and what you see are the dark spots of the scale and decarb.

As I mentioned earlier, there are several finishes available on a bar of steel. There are Hot Rolled Annealed (HRA), cold rolled annealed (CRA), pickled, blanchard ground, precision ground, and some others. Each has a different look on the surface, but is the same inside.

Unless one is using precision ground stock, the surface should always be sanded back a few thousandths to remove the surface scale and decarb. Many makers run their blanks or the whole bar through a surface grinder to remove the surface and make sure the blank is truly flat.

I take my profiled blanks to the flat platen and flatten both sides to remove any scale as well as assure complete flat sides. I add the basic distal taper at this time, too. I repeat it again after HT to remove any minute warp and the new decarb.
 
I have gotten a few small black dots after HT on 1084 from Aldo. I have just left them alone as to sand them out would change my blade geometry more than I wanted to and I wasn't selling them, they were gifts.

My process is as follows. Cut out, grind profile, grind flats on my flat platen till I have a uniform scratch over the entire surface removing mill scale. My platen plate is 16" so I can do the entire blade at one time switching directions about ever 15-20 seconds of grinding. Sand flats to 120 grit on my surface plate to ensure flatness, grind bevels to 120 grit leaving .020" at the edge. Heat treat, repeat the same process on platen and surface plate, to remove decarb bringing edge down to .010". On 3 of my knives I have had 5 small black dots appear after HT and sanding off decarb.

Mind you I have a guesstimated HT process heating till non magnetic and just a little more heat (PID and thermo couple are in the mail from auberins). I did not have an accurate temp reading for the HT so that may be why they appeared. The dots were a little bit bigger than say the tip if a tooth pic and a deep as say the thickness of a fingernail. I also did not use a muffle, but have one now, so with the PID and thermo couple that are on the way, my HT process will be much more precise, so this may eliminate the dots I was getting. These shouldn't be patina as they haven't had time to patina, they were fresh ground blades.

I only have one of these blades left in the shop I could take a picture of, but it is acid etched with FC, so it would do no good to try and show it.
 
Stacey and Mr pleasant Hill, thank you. Very much. I believe I understand now. And im about to purchase a 2x72 , excited.
 
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