What is wrong with this steel?

L

Lo/Rez

Joined
Feb 10, 2013
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1,019
I made this little chopper out of AEB-L and the steel has 'something' wrong with it. It's the second time I've had this happen to one that I've heat treated. I follow the same procedures every time. It looked fine prior to heat treat.

IMG_20150512_205904_zpsqpuvbnug.jpg
 
Looks like an artifact from HT. How did you do the HT, and how much sanding was done post HT?
 
If completely uncompetent people are allowed to participate... could this be decarb if there was a puncture (or porosity) in the foil it was wrapped in for HT?
 
I sanded it to about 500 grit, wore nitrlile gloves when I cleaned it with acetone, high heat stainless foil with triple folded seams (a little piece of brown paper bag in the pouch) put them in cold, followed the Alpha Knife Supply recipe, plate quench followed by dry ice mixed with denatured alcohol and then tempered it. This is the second time I have come across this (both along the spine) so maybe I inadvertently contaminated the process somehow.
 
Was the spine sanded/ground any post HT?

One reason I don't put in paper is it usually just makes a dark stain on the blade anyway. I spray with a light coat of WD-40. I always go back one grit lower than the final pre-HT grit when finishing. On your blade I would have gone back to 220 grit and re-sanded all surfaces, then gone up the grits to whatever I wanted.
 
I would hazard a guess that if you ground down halfway through the blemish it would still be there. I know that it shouldn't happen on good steel, but I had it happen on S35VN.
 
I am also under the impression that that spot won't go away with sanding.
It is possibly a carbide situation, if you had ht'ed it into a forge that spot would have been exactly under the flame, but i bet you did use a kiln and the situation was already there.
 
When they roll it out, it's laminated with carbon steel as a sacrificial protective layer.

It could be they missed a spot when trimming it off.
 
12345678910 said:
When they roll it out, it's laminated with carbon steel as a sacrificial protective layer.

It could be they missed a spot when trimming it off.
Click to expand...

I didn't know it, if it's true than that spot is surely like the effect of a tack weld. I would have the steel replaced from the vendor.
 
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