newest knife! but whats this on the blade?

C

clockworkfish

Joined
Dec 1, 2010
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161
Cnc'd walnut handles, brass pins, 1080+ hi carbon steel from aks

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Super comfy in the hand

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while sanding it this came up and im not sure what these little bubbly looking things are , should i be concerned? Reminds me of a hamon in the way it is visible but a very different pattern.

When i quenched the steel i went straight down into a coffee can filled with warm canola
steel was austintized at 1560 +/- 10 degrees and tempered at 420 (this was based off the heat treat charts on alpha knife supply for 1080+)
 
no, just realize there is a skin of decarb to get through before you get to the good stuff, not a big deal, just a bit more sanding

-Page
 
Agreed,
Many folks don't take enough off the blade after HT. I go back to 120 grit and strip the blade to bare metal post-HT and then go back up to 400 or higher.
If doing HT in a forge, make sure the atmosphere is right. You want neutral to slightly reducing. Too much oxygen will lead to much deeper decarb.
Decarb is a normal and natural product of heating steel above 1300F. The higher the temp, longer the soak, and more oxygen in the atmosphere...the deeper the decarb.

A satanite/clay wash on a carbon blade may help slow down decarb, but I suspect that oxygen doesn't see a little clay as much of a barrier if the conditions of the HT aren't right.
I have used Turco for years, but I don't know if it is available anymore? ( good thing I buy things in large quantity) Turco is a boric acid and yellow ochre mix. It seems to have a thickener like gum tragacanth in it ,too. When I finally run out, I will either find a source, or make my own mix up.
 
I just realized that that has been my problem with some streaking on my blades. I haven't been going to a low enough grit to get to really clean steel. Lesson learned.
 
Thanks Don. That's definitely been my problem. I really thought since I had it to 400 pre HT my 240 belts should be plenty. I realized last night that as I dropped back down on the next blade to 80 grit suddenly I was at bright steel with no streaks. The advice confirms what I realized last night. I appreciate it.
 
I posted about something very similar last week and you guys confirmed it as decarb for me. Thank you. What I want to know now is how do you "tune" a forge for a reducing atmosphere? Are there ways to test it besides just seeing the results of a HT (if there is less decarb than last time)?
 
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