Another de-carb question

It’s essential for almost any steel depending on the condition the steel comes in, last I checked Njsb couldn’t say what state their 1095 is in so therefore it’s a process that is necessary. Check out the book Knife engineering by Larrin it explains a lot of important information about steel and heat treating and I think it’s only $30, I promise it will be the best knife making investment you ever make.
I just did some .125 1080 blades today at 1470* no soak in canola and they passed the file test and the decarb/scale looks minimal.
 
A few things that might help here:
  • Take another look at your soak/recovery times. For a kiln your size, it will take 4 to 5 minutes after kiln recovery for a blade that size to come up to temp especially if you back it off to 1475 (at least it does for most folks). Then start your soak. Technically, 1095 just needs to come into solution but I've seen it help. I have seen this weird thing where you can get what seems like a thick layer of decarb that seems to clear up about 30 thou deep, but upon requenching with a longer soak at the same temp the exact same blade is now hard as a coffin nail right under the surface. I have no explanation for this, but I have seen it with my own eyes. Seems totally backwards, but there it is.
  • Your kiln and mine are about the same size and wattage (yours comes up way faster than mine though!) but I'd let your kiln soak for like 30-45 minutes once it hits target before using it. It helps make recovery and soak times more consistent across batches.
  • The Parks 50 is worth it, in my opinion, and agitation is really important. I'd avoid letting your Parks go over 90F if you end up going that route.
  • If you don't want to mess with all that, try a multi quench as an experiment. If things suddenly improve once you start quenching multiple times, you probably want to take another look at your thermal cycling regimen or soak.
 
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