air hardening heat treat question

blgoode

blgoode

Joined
Oct 3, 2003
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I have an even heat and have had great success heat treaing A2 and D2. Foil wrapped and plate quenching single blades.
My question is that I have read somewhere A2 had a long window from final heat treat temp to getting below the curve to fully harden. Meaning you have a large window to get the knife out and wrestle it from the foil pack.

If I have 5 small D2 knives in a single foil pack, do I have a long window to take them from said package to air cool?

I am used to a rapid oil quench so this time from critical temp to below the curve is new to me on foil wrapped steels.
 
Brian,
I wouldn't worry about it, with A2 you have at least 6 minutes to cool it down and miss the pearlite nose. Its an air cooled steel, you might be pushing the transformation a bit hard by quenching it in oil, even a slow oil. This could induce stresses that you might not be able to relieve by tenpering.
Del
 
I have always cut open the foil packets, taken out the blade and just let to still air quench.

The 1/16" blades obviously cooled a lot faster than the 3/8" stuff i've done !
 
D2 does have a long window, but I can't seem to locate a ttt diagram for it, so I can't tell you how long.
Thanks,
Del
 
It is about same as A2, not sure but about 5-6 mins. But a faster quench will increase the corrosion resistance... Plate quench is more convenient and keeps blade's flats flat...
 
"Tool Steels" by Roberts has the diagram. Nose is at 1300 F and you have about 7 minutes to get past that. Plate quenching is still the most convenient .
 
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