PDA

View Full Version : Foil Wrap



watercrawl
06-17-2011, 04:32 PM
Heat treating stainless steels and I have a question or two.

What does foil wrap do? I've read that it keeps the oxygen out and creates a sort of mini-vacuum. And? I haven't been able to hunt down the reason that's good or necessary.

What happens when you don't use it?

Darrin Sanders
06-17-2011, 11:35 PM
Foil holds decarb/scale to a minimum. Properly cleaned and wrapped blades should come out of the oven looking almost like they did when they went in.

Knifemaker.ca
06-18-2011, 12:41 AM
Most stainless steels are hardened from temperatures 400 - 500 degrees hotter than carbon or tool steels - and they need to be soaked at that temperature, often for 30 - 45 minutes. Unprotected steel gets bad decarb and scaling at those temperatures - at best requiring heavy stock removal after heat ttreat and at worst, ruining the blade completely. There are lots of ways to protect the blade - forge atmosphere - Turco - ATP641 - various powders, but foil is less messy than most coatings and, done right, yeilds a real clean blade.

Tom Militano
06-18-2011, 05:02 PM
I really like the foil wrap. I quench my CPM154 between aluminum quench plates and the blades come out pretty much like they went in the foil wrap.

watercrawl
06-19-2011, 12:00 PM
Thanks guys....appreciate it.

watercrawl
06-21-2011, 08:46 AM
Can the foil be reused? Before I order enough for all of the blades, wanted to check.

watercrawl
06-21-2011, 09:04 AM
And I hate to be a cheap ass, but will this work upto 1,950 degrees?

http://www.usaknifemaker.com/heat-treat-foil-tool-wrap-321-afi-002x20x25-up-to-1900f-p-2798.html

I know I could ask Tracy, but I'm asking here.

Title says 1,900, but text says 2,000. Anyone try it over 1,900 degrees?

Knifemaker.ca
06-21-2011, 09:47 AM
Some people re-use foil - and sometimes it fails when re-used ruining a blade.

Sometimes 321 foil does fine at 1950 - and sometimes it either fails or welds to the blade.

I know you'd like a "black and white" answer, but this is one of those 'maybe' things. Here, we only use 309 foil and we double wrap everything. That's because we are doing someone elses blades. If I were only doing my own, I might take a risk on some blades.

Rob!

watercrawl
06-21-2011, 10:13 AM
Fair enough. :)

Thanks!