Does this heat treat sound OK?

[the possum]

I have posted this over on swordforum, hopefully you guys could read that thread so I won't have to retype all the details.
heat treat question

Basically I'm making a great big Bowie knife for heavy chopping, and I want it to last. I first thought I'd send it to a guy in Texas and have him to a clay coated quench, leaving 2 hard edges with a pearlite body. Now I'm rethinking the whole deal, and may send it to a different guy to do a salt pot marquench, leaving the whole blade Bainite. From what research I've done, many smiths now believe it will produce a better blade for chopping, strength, etc., at the expense of a little wear resistance. Could I have some opinions on this?

Thanx.

 

[Guy Thomas]

I don't see how you could go wrong with a bainite blade in this circumstance taking into consideration the use of the blade. By all reports bainite is practically indestructable and just gives up on the edge retension front. Howard Clark has perfected a method with his L6 swords where he has obtained a bainite back and a martensite edge on the same blade. Years ago he was forthcoming on how he achieved this but no one was interested at the time so now he keeps it under wraps. I can only speculate on the general process he uses to achieve this but I do know it must be very time consuming and difficult.

As far as using the clay coat method on 5160, since it is a deep hardening steel I have heard of 5160 blades that may break and separate along the hardening line. One method around this I have read about is to through harden the entire blade and then do the clay coat and quench again. I've had no direct experience with 5160 and clay coated quenches however, so hopefully I'm not propagating a myth here.

As an alternative to producing bainite (which takes an extended amount of time, like ten hours or more, at a particular temp) I'd suggest using the salt pot and through harden the blade by marquenching. The resulting blade would be much tougher than a standard through hardened blade with little risk of bending. I've heard of demos where a marquenched and untempered blade was dropped point first into concrete with no damage to the blade. This is how Kevin Cashen heat treats his swords and they perform well by all accounts too (and on his monosteel blades he is also using mostly L6).

In my opinion the standard edge quench (fine pearlite back and martensite edge) should also serve admirably in this situation, especially if the triple-triple-triple method of heat treating (used mainly for 5160 and 52100) is used.