File scratches after hardening.

T

Temujin H-Pinchers

Joined
Oct 22, 2020
Messages
12
Hi there,

I've been making a few blades out of 52100 steel. I followed the heat treat guide at knifesteelnerds and right after the quench, a file will still scratch the surface of the blade. I played around with a few different HT's and got the same result every time. However, on one blade I continued on with the hollow grind and a file will not mark the steel after grinding. I'm wondering if there is a layer on the surface of the steel or something.
 
The surface of the blade loses carbon during the heating cycle and ends up with a skin of unhardenable steel which has to be ground off, even if there is no visible scale.
The depth is usually very shallow but can get deeper with multiple heating cycles.
 
Thanks for the help so far. I do use the stainless steel foil to protect the blades in the oven so I didn't really expect any decarb. I've seen many videos of people austenizing unprotected where you might expect decarb but they get that skating file. I wonder if the alloy is just more susceptible.
 
DO NOT USE FOIL for HTing a 52100 blade ... or any carbon steel blade. You won't get full hardness.
Carbon steel needs to be quenched immediately into the quenchant with surface contact ton the oil. If not the steel will not harden evenly , or perhaps at all. Decarb is not a big problem with HT on carbon steel.

Air hardening steels are where you use foil to prevent severe decarb.
 
You must log in or register to reply here.
Back
Top