Flakes of steel: Heat Treat Question.

[Runthemall]

During the middle of heat treating an O1 knife blade today, I noticed it started bubbling and flaking. Is that bad? I'm use a coffee can forge and was trying to hold a dull cherry red for 10 minutes. After about 4 minutes it started doing this, so I panicked and quenched it. It definitely hardened, but is the quality of the steel compromised?

Also, there's a bunch of black flakes in my canola oil.

 

[MadBug]

A Guess. A low temp forge, lots of oxygen, lots of soak time, lots of scale. Soak it in cider vinegar overnight, and take a look at it. It should just be scale.

 

[S.Alexander]

It's just heat treat scale. It will come right off with your final grinding and sanding. Just make sure to grind and sand past all of the decarb.