Need help with 52100 HT

[Huntsman Knife Co. LLC.]

Hey guys,

I am making some integral Hawks in the near future from .22 52100 and want to go with the best heat treat possible for both edge retention and toughness. I will be sending them to Peter's.

Ideally, I would like to go with a differential HT with a nice hard cutting edge and spike around 60-61 and the rest of the body and head left at spring temper. However Im worried that a spring tempered body will be too soft and end up bending during hard use. All of the hawks will be handled with .375 thick slabs of G10, micarta, or wood all the way to head.

Will a differential HT leave a body that is rigid enough to resist bending under hard use? Or Should I go with a through hardened hawk and bring down the hardness to about 59-58?

Thanks in advance! I cannot overstate how helpful this forum has been in the development of my skills and understanding as a knifemaker.

 

[Rick Marchand]

You state "differential heat treat" and I find that a bit confusing. There is differential hardening and differential tempering... they are separate treatments.

In differential hardening, the conversion to martensite is selectively inhibited in some way, either with clay, edge quenching or selective heating with a torch. You are left with a martensitic edge, while the rest of the body is a mix of pearlite(and other stuff) with a transition zone between the two. This type of structure is prone to deformation.

Differential tempering is applied AFTER the blade has been fully hardened. With a prominently martensitic structure, selective tempering methods are used to draw back hardness, increasing toughness. Martensite is much stronger than pearlite, so it resists deformation.

If you want a hawk that will spring back true, differential tempering is the way to go. I'm not sure what Peter's HT offers. If they don't do differential tempering, have the fully harden the whole piece. When you get it back, put the edge in a shallow tray of water and draw back the body with a torch to a blue spring temper.