Soak temp and time for 52100 and 5160?

The reference is a patented process, though the time for the patent has expired. It applies to a variety of steels, though 52100 is specifically used as an example.

http://www.google.com/patents?id=MA...urce=gbs_overview_r&cad=0#v=onepage&q&f=false

There is another patent below. This one builds on the former, and even expands to include some A2, an air hardening steel.

http://www.google.com/patents?id=Me...urce=gbs_overview_r&cad=0#v=onepage&q&f=false

The basic process seems to be heating to a high enough temperature to dissolve all the carbides, then cooling using a method that prevents precipitation of new carbides or keeps them very small. Oil quenching, marquenching, austempering, and fine pearlite formation are mentioned as suitable means.

Following the carbide reducing step, rapid austenizing is employed and quenching follows. This is a very basic over view. As always, the devil is in the details.

The time-temperature-transformation curve in the second reference shows the effect of grain size on transformation times. The dotted lines started with a grain size of 9 and the longer times of the solid lines started with a grain size of 3. Larger numbers mean smaller size, like sanding grit and shotgun gauge, for anyone who doesn't know.
 
Me2 -Thank you for those references! I sure would love to spend a few weeks with those gentlemen, naturally with a power hammer, shop and Lab. to play in.
 
Unfortunately, I'm not sure if they are still practicing, or even still alive. The newest patent is older than me (35 years). The other is even older. I think patents expire after 17 years, but it may be industry or topic specific.
 
lady knife is over 4000 years old its truly hard try something thats not been done or a shape thats not been formed
we all are jsut stepping on the stairs of the makers of past

now the only trick to this is if you go and use high tec in any way to process the steel after all if you use the old ways they have often been "fixed" because of trial an error (well less you are using a steel that was never meant to be used "old school")
 
We can learn about blade geometry from knife makers of over 1 million years ago, back when most knives made sense.

Today we have the best steels ever available, much if not all we do has been done before, the big difference is that now we can share information in seconds and for each knife maker his greatest competition is with himself.

While we can find many methods in written material, just think about how much information has been lost before makers shared information and never being written down now waits our attention.

A maker sent me a metallurgical text book written in the 30's. The authors of one experiment tried multiple quench on 5160. A footnote mentioned that their method "resulted in the finest grain structure they had ever observed in 5160."

I feel that we still have a lot to learn and will continue to do so.

One index of success I find useful is when we reach a balance point in performance when an increase in toughness results in a loss in cut &/or some other functional aspect of performance.
 
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