Differentially Heat Treated Stainless

[Crayola]

A year or so ago Paul Bos wrote in this forum that he has differentailyl heat treated stainless, and that if someone would call him he'd share the how to's. So, I did just that and typed it up here! Now, the Bos method that was elated to me was how to draw the back to a softer state, which isn't the same thing as a stainless hamon. But if ya run a search on this forum, you can get those instructions anyways!

On a side note, calling Bos was one of the ebst things I have done with respect to knives. I have since called other knife folks, and it is well worth the few $$ it costs to talk with other knife folks on the phone! I called Rick Hinderer a few weeks ago and he told me TONS about mills and what to look for and what different sized mills can do. One of the best things about the knife world is that you can talk with any maker, for the most part, and you get an excited knife nut willing to share! Pretty cool.

 

[rlinger]

Very well stated Chuck, regardless of my German decent.

RL

 

[Gabe Newell]

In my interactions with Thomas he has always come across as very thoughtful and professional. I'm curious to hear more about his process and what benefits he gets from it.

 

[Dan Gray]

I've done it
and it is more of a pain to do than the carbons
the biggest benefit is working the rest and the tang
after the fact, as someone said before.

if the soak time and quench at the edge is
right then you'll have no problems

I've been working on different ways to make it easier.
but as far as a benefit in bending to 90 plus deg's
you may want to stay with the carbon steels.
I didn't vote it's not there for me.

 

[rlinger]

Dan, what is the most difficult about it? Getting out of the foil quick enough??

RL

 

[SDouglas]

I would be interested in having a blade Rockwell tested on either side of the Hammon to see what the difference really is.

That would provide more insight into the benefits.

 

[Dan Gray]

Roger your going to kick yourself once you think about it.

The problem is, it's an air quench steel
so you'll have to stop the spine from quenching (from the cooler air )
if you heat the whole blade as you like to do.,

and to anneal SS it's a
pain in the A$$ trying to keep the edge from heating back up with the time it takes to do so.

if you want to truly edge quench the edge of
most of the SS's you'll have to heat
only the edge and let it quench leaving the rest cool..

440 is not to bad with it you can use a
torch if you are careful but it's nothing like Carbon steel
as far as ease and being right.

 

[rlinger]

Dan, that did not escape me originally but what you say gives a better insight into the difficulty of having a much softer spine. I was thinking in terms of maybe a couple points or a point and a half difference. The way you look at it would maximize the differential. This indeed does put it in a class truely unique to differentially heat treating carbon steels.

SDouglas,

It would be very difficult to correctly Rockwell the beveled blade because of it not being flat. There are different anvils available for Rockwell testing flat, round, and concave but I have not seen or heard of a setup that would allow precise testings of blade geometry.

RL

 

[Dan Gray]

I thought you may have been thinking that way.
they want the full pot of beans though..

the ones that grind after the heat treat can heat sink the
area to be soft then grind after the temper this would be a good
way for them. that's one way of doing it..

 

[rlinger]

I would like to hear of some real benefits in differential heat treating of high alloy other than just looks of a hammon. So far, if I have read all this thread correctly, I have seen none expressed. You mentioned the strength test (flex) but it is assummed high alloy is not expected to do that well compared to carbon steel. Am I mistaken?

Like with you, it is the challenge that intrigues me.

RL

 

[Dan Gray]

The only real benefit I see Roger, is being able to work
the rest of the knife at will after the heat treatment.

this is the one thing I like about
edge quenching and differential tempering carbon blades
other than the hamon that many like to see..

I'm always treating SS and forgetting to do file work
getting old

 

[rlinger]

I see your point Dan and neglected to remember you had already mentioned that in a earlier post.

RL