Post Heat Treat Grinding - why bother with foil wrap for HT?

C_Claycomb

C_Claycomb

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Dec 11, 2000
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I have been reading a lot of threads about heat treating lately and two things seem to stand out. A lot of people doing most or all of their grinding post heat threat, particularly in AEB-L, and oft-repeated advice that stainless blades need to be wrapped in foil to prevent de-carb.

If a maker is going to do all bevel grinding post heat treat, and so grind off any de-carb on the bevels, what is the benefit to using foil wrapping?

Chris
 
One thing I can think of for sure is the funk you'll get on the ricasso. On paper at least, you'll grind the edge back enough to beat the decarb. In reality, your flats are going to be ugly and it's hard to accurately remove material along that dimension. I suppose IF you started with slightly thicker steel, and IF you tapered the tangs, then you could surface grind the ricassos and get the gunk off. It's easier to just use foil, or even easier to use anti-scale like this: https://popsknife.supplies/collections/nuclayer
 
Also, with some steels with long soak requirements and very thin cross sections, you could end up with very little actual good steel left.
 
some doing stainless often go much higher in grit pre heat treat. some go to 1000 grit. the foil keeps the decarb away so you dont need to go deep to remove it.
 
ive had pinholes in my foil once or twice and cn tell you on 3/32 XHP and cpm154 at 2000f for 20 min soak the exposed steel is completly trashed no amount of grinding a bevel would fix it you have to reprofile the blade to grind away the decarbed steel. no foil woudl trash the entire blade
 
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I would think that when doing work like this, Jurgen would probably do everything imaginable to keep decarb from happening. Last I saw, this knife had a $160 000 bid and it probably went up from that insane number. To my way of thinking, cutting corners like skimping on foil is a sure way to avoid making the kind of money that Jurgen does for his work
 
A.McPherson said:
Is it just me or does that thing look like an imperial star destroyer from starters star wars?
Click to expand...
it's art, man- whatever you want it to be!
 
I am generally fairly happy to make about 1/800th of that per knife...I don't think that there are THAT many corners that I can cut!

My question here was somewhat related to my other thread about a commercial heat treater here in the UK offering treatment for stainless, but using anti-scale coating instead of foil or inert atmosphere. I have read generally negative opinions on here about anti-scale coating for stainless and was wondering what the worst would be if it didn't work and if one was grinding after the HT. Sounds like one should hope the mud does the trick!
 
no decarb, no problems!
 
I won't use anything but foil for heat treating stainless blades. In my experience, the anti scale coatings don't work that well at those temperatures. They work great for carbon steels heat treating up to about 1750°F, but struggle with the higher temps. Even ATP-641, which is rated to something like 2300°F, still has decarb issues heat treating stainless. Granted, it cuts the decarb depth by a lot, but when you have a blade at final dimensions/finish going into the heat treat, and then have even just the smallest decarb, it can be a problem. The cost of the foil is well worth it.
 
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