Hello guys...

My steel agent here selling steel from Germany (Thyssen Stahl AG) those are A2 and D2 on AISI standard (air hardening steel as far as I know), but the data sheet tells us that we can hardened it on oil or air!

If it is true, is it meaning that we can edge hardening those steel type? And what about the hardness level are there any differences with air hardened?

Please give me some insights bros... THX & GOD bless you all

Frids Laguna

A2 and D2 should be oil hardened if they have large differences in mass to prevent cracking at the intersection. For instance, if you were making a machine part or die detail out of 2" thick material stepped down to 1/4" thick on one end, that part would need oil hardening to prevent stress cracks at the step. You would have to leave excess stock to grind off after the quench.

For knives thinner than 1/4" or so, unless you have a large step somewhere, an air quench will do fine, and prevent all the scale and twisting caused by a sudden oil quench.

The thinnest part of the knife (edge) will cool faster.

I don't believe edge hardening will work to your advantage. These steels cool to below the transformation range very quickly. A partial quench would probably cause stress fractures. :(

THX a lot Mr. Robinson, I think I get what you inform me about the cross section of the tools compare to a knife. See you around, God bless!