question about stress relief of D2 (in foil)


Well-Known Member

I'm preparing to do my first in house HT (quite literal in my case since my HT oven is in the kitchen!)

I want to do a stress relief before hardening, from supplier data sheet:

After rough machining the tool should be
heated through to 650°C (1200°F), holding
time 2 hours. Cool slowly to 500°C (930°F),
then freely in air.

I will probably heat following that process but let it cool in the oven

I will be using foil, do I have to change foil? or use the same one after that for the hardening process?
and is 2 hour too much for a knife? (aprox 5mm thick)

(any other tips or info for the HT process is welcome)

You don't need to use foil for stress relief. The layer of scale that build up is minimal.

I do the full 2 hours for stress relief. You may not need the full 2 hours, but I see no reason to cut it short to experiment with it.

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Dealer - Purveyor
Using foil and plate quench, you have the ability to have blades come out of heat treat almost as shiny as they went in. After 2 hours at 1200F, unprotected, they will definitely not be shiny. This is probably another one of those things to try different ways and decide what you like best. Foil is expensive. Post HT clean up is a PITA.

I haven't had much luck using foil for multiple cycles, but there are makers who regularly reuse their foil and swear that it works fine for them.


Well-Known Member
agreed on the post HT clean up!! thats why I got foil to begin with!


I decided to go with foil and see