Heat treating and cutting capbilities...

B

BrB

Joined
Sep 16, 2003
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In the short absence of our foremost trouble maker I thing I can start something to shake things a little.

I often see knifemakers stating the great qualities of their heat-treatment methods and the cutting capabilities of their knives.

I always thought that the factors in this process where limited to the carbon content, the alloy elements, and such things resumed in the appropriate temperature for each step of the heat treating process and the quench medium.

So, if you know what your steel is, you know it´s best temperatures (or you are good with the magnet) for quench and tempering, and you know any other procedures that apply to your steel (such as cryo treatment), you WILL GET the best results possible. And all that information is clearly available in charts and books.

So what can be different from one knifemaker to another in this area? I understand that damascus should have the math worked out for the average carbon content, and that different quench media should slightly alter the results, but in hardness therms, how much difference are we talking about, from maker to maker? Or better, from method to method?

The reason I ask all this is that statements such as Shiva´s for example really bothers me (to name only one knifemaker). So what makers can add to this subject? And how do collectors see this aspect of their knives?

Jeff Velasco
 
BrB said:
So, if you know what your steel is, you know it´s best temperatures (or you are good with the magnet) for quench and tempering, and you know any other procedures that apply to your steel (such as cryo treatment), you WILL GET the best results possible. And all that information is clearly available in charts and books.
Click to expand...

99% of charts and books available are for industrial heat treating, most assuming a 1" thick section of steel. As knifemakers are dealing with much smaller cross sections, they must research their own heat treating methods specific to their HT setup, kiln, or forge. Additionally, the steels available can vary wildly. 1095 from one distributor will be different than 1095 from another, and vary from batch to batch as well. There are fewer steels available specifically made for blades, so the controls on their contents can vary. What is "acceptable" from an industrial standpoint may not be for a knife if you are looking for the most you can get out of the steel.

As a result, the human element in HT becomes the maker's choice of HT method (forge, kiln, torch, salt bath, etc), their choice of quench medium (goop, veggie oil, HT oil, synthetic oils, paraffin based oils, etc), and their testing method to ensure the results are what is desired.

If you take carbon steels (for example 1095), you might be talking about less than 3/4 of a second to get the blade ourt of the forge from above critical to quenched and below the nose. .75 seconds is not much time, and no book or chart is going to tell you how to "get it right."

All these factors can cause large variations on makers' results. Some have prefected the process through testing, modification and repetition. Some outsource their heat treating, and others go purely on performance and ignore what is "right" and "wrong" from the books so long as they are getting the desired results.

With so many steels, methods, techniques and variables, consistency is only as good as your process is developed and tested.
 
also, the HT specs from the manufacturer are kind of "lowest common denominator" if that makes any sense.

whereas a knifemaker is trying to wring every last bit of performance possible, and good enough isn't (or shouldn't be)
 
Great post David, cleared a lot of issues. Let´s see what else comes up.

Jeff Velasco
 
Steel selection and heat treat are only part of the story. Blade and edge geometries are just as important. You can take a hardened prybar and grind it to an edge that will shave, but it will be a inferior cutter unless the bevel facilitates its slicing ability.

Ergonomics is also important. How does it fit your hand? Are you able to make the motions needed to cut well conformtably?

One quick word on heat treats, never shorten soak times. Many makers will note that manufacturers will give a minimum time per inch of thickness and say that since the blade is only a small fraction of an inch thick thay they can shorten the time at temperature. Not so, the minimum is what it takes to disslove the various carbides. This also happens at different temperature ranges depending on the type of carbide.
 
BrB said:
The reason I ask all this is that statements such as Shiva´s for example really bothers me (to name only one knifemaker).
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Hi Jeff,
To which of Shiva Ki's statements are you referring?
I have a number of his knives and find them to perform very well,there are others on the forum who do as well and as far as I know
they tend to agree with me on the performance aspect of his blades.
Just wanted to get that out of the way as I'm sick to death of Shiva Ki being bashed at every opportunity that presents itself.
Hope this turns out to be a good thread about Heat Treating and cutting capabilities.

Doug
 
I am not a knife maker or an expert on steel but i use knives alot and in my opinion Heat treat and edge geometry are everything. I have gotten knives of same steel similar edge geometry and some seem to hold an edge longer some sharpen easier and so on. Different makers have different aproaches at what they deem the best happy medium on there blades. Just got one of Shiva's blades and sent it out for leather. I was impressed enough to order another and should have it soon















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Doug C said:
Hi Jeff,
To which of Shiva Ki's statements are you referring?
I have a number of his knives and find them to perform very well,there are others on the forum who do as well and as far as I know
they tend to agree with me on the performance aspect of his blades.
Just wanted to get that out of the way as I'm sick to death of Shiva Ki being bashed at every opportunity that presents itself.
Hope this turns out to be a good thread about Heat Treating and cutting capabilities.

Doug
Click to expand...
Could we be talking about a slight case of the D.E. Henry syndrome? I have never owned not handled one of Shiva's knives, but everything I hear about them leads me to believe that he makes one very find cutting tool. With that said, reading his website caused me to raise my eyebrows just a tad.
 
Great question Jeff!

Personally I think this is one of the biggest areas of "hype" in the custom arena...

That's all I got on that :)

Doug, while I wasn't impressed with how Shiva handled himself here on the forums, I am quite interested in whatever it is that he does with his heat-treat and edge geometry. I'd love to use one of his knives someday and see for myself :)
 
I'll use D2 as an example.

When my shop was doing tool and die work I used the accepted industrial heat treat practices for that steel for my applications and was rewarded with a high performance die steel with good abrasion resistance. Great.

When I started making blades in D2 I realized my heat treat, from the book, wasn't optimal.

For starters, D2 is designed to retain austenite, to prevent growth and dimensional changes associated with martensite (less dense=larger piece) While this was never an issue in a die, it caused edge stability problems because a matrix of hard martensite, carbides, and weak austenite shows up an a thin edge that you would never see on a punch. There are many ways to address this issue. Cryo is one, but even it will not convert stabilized austenite, so your timing for cryo (before any tempers, or much delay) is not "in the book" because it wouldn't work well for most industrial applications.

Secondly, a tool shop often tempers to the secondary hardening hump. For a blade, this causes unwanted grain boundary carbides, less corrosion resistance, and weaker martensite with bigger carbides. That causes a weak edge.

A tool shop air quenches D2. But just "getting under the nose" isn't the whole story in a complex high chrome steel. The rate of quench can effect hardness and corrosion resistance.

The day before yesterday I used a fine thin D2 hunter/beater knife in a production environment hacking away at a lot of plastic and popping through into an old wood pallet for four hours. Lots and lots of cutting. The scrap filled up a large box. At the end of the day and very much abuse the knife would still shave hair, even on the belly which was the most abused area. It took me time and experimentation to nail the heat treat for this steel to achieve this level of edge retention, and that information is not found in a book.
 
I'm not sure that most makers are "hyping" up their heat treat so much as explaining our test methods to alleviate any angst our potential customers may have.

Given the same steel shaped into knife geometry, 2 different makers may take very different routes to "nail" their heat treat. Break the blades and you'd probably not be able to tell the difference in the heat treat although the methods were very different.

The differences in the makers "hype" would be from their experiences using knifes and what they want out of one. One maker may prefer a harder edge to gain a little more wear resistance, another may want one easier to resharpen... we're all victims of our expectations and tend to make knives that handle and behave in a manner that we want them to.

I hope this is coherent, I just got off of work and am kinda wonky on coffee.
 
Optimal heat treatment is only the first step in achieving optimal cutting performance. And, while there is no "magic" involved in achieving the best heat treatment for a given steel, there are lots of little subtleties that do make a difference. How many makers do their own heat treatment, yet don't own a calibrated Rockwell tester? Quite a few.

Cutting performance depends a great deal on blade shape, grind style, edge thickness and the edge itself. Because there are many different types of cutting that can be done, from chopping wood to slicing tomatoes, achieving the optimal performance means that the maker has to understand how to factor the final use of the knife into the execution of the blade. He also has to understand how the properties of the steel he has chosen and heat treated can contribute (both positively and negatively) to the performance of the knife.
 
jdm61 said:
Could we be talking about a slight case of the D.E. Henry syndrome? I have never owned not handled one of Shiva's knives, but everything I hear about them leads me to believe that he makes one very find cutting tool. With that said, reading his website caused me to raise my eyebrows just a tad.
Click to expand...
Joe,
SK's website was designed by a kid,4 or 5 years ago.The only one I know who's more computer illiterate than me, would be Shiva,but I'm learning a little, thanks to some of the good folks here.
From what I hear tell about Ed Henry,he was an irascible,old SOB who would have done a heck of a lot better if he would have adopted a kinder,gentler approach.IIRC,his wife was a nurse and brought home a steady paycheck which allowed D.E. Henry to pursue his knifemaking.
If I am disemminating any misinformation,somebody step up and set me straight.
I really like his knives and would love to acquire an example.
Yitz!? :D

NickWheeler said:
Great question Jeff!

Personally I think this is one of the biggest areas of "hype" in the custom arena...

That's all I got on that :)

Doug, while I wasn't impressed with how Shiva handled himself here on the forums, I am quite interested in whatever it is that he does with his heat-treat and edge geometry. I'd love to use one of his knives someday and see for myself :)
Click to expand...
Nick,
I don't think many were impressed with SK's posts and I'm not gonna' try and apologize for him,again.If a horse was ever beat any deader than that one,I haven't heard about it yet.
If you are interested I'd be happy to send one to you to play with,it will be a wood handled, small Spirit blade.
No iron sand,jewel steel mystery blade here, just a straight 1095 fighter styled knife, just send it back when you're done.Let me know.
Everyone else,
I'm not marketing or spamming for SK,just trying to give back something to this great place where I've learned quite a bit.

Doug
 
I was thinking of the "stand-out" makers when I said hype.

I continue to try and improve my heat-treating every time I do it... part of that was building my digitally controlled salt bath and adding a Rockwell tester to the shop and the digital kiln (which isn't working right :grumpy:)

I've tested more blades to destruction than most any sane person would and I've come to a point where I am comfortable taking my knives down to a much thinner edge than most makers use.

But it's all just trying to make the best knife I can.

My knives still won't hack off a parking meter stand or knock a tree down in one swing.

Nothing I do is any kind of magic or mystery.

Well, except for maybe the hamon thing ;)

The fact that there are quite a few guys who stand out in my mind as shouting from the roof-tops on how much better their heat-treating is than everyone elses is what I connected to this thread and why I used the word "HYPE" :)
 
Since we are basically all using the same steels, the issue is quality control throughout the whole heat treating process. Accuracy and repeatability. RJ is a master at it.

Dan
 
Jeff,

I agree with you to an extent. I think there are several elements that explain these discrepancies:

1 - Different makers have different ideas on the optimal hardness v. toughness compromise. This is a legitimate difference.

2 - Thin cross section HT is still being researched, and largely in a less well "lubrified" information sharing medium than academic research, so the right methods are still being refined and take time to permeate.

3 - Makers might use different tools that require different MO, e.g., salt baths v. furnace.

4 - Some makers don't want to deal with or can't afford the right tools (e.g., salt baths, digitally controlled furnaces, etc). A lot of good and otherwise serious makers like the aura of mystery that surrounds fire & steel, and they are reluctant to "unweave the rainbow".


If I were you, I wouldn't pay too much attention to what Shiva Ki says. He is the uber-hypist. It doesn't mean that his knives are bad, but I wouldn't worry about what he says.
 
Doug C said:
Joe,
SK's website was designed by a kid,4 or 5 years ago.The only one I know who's more computer illiterate than me, would be Shiva,but I'm learning a little, thanks to some of the good folks here.
From what I hear tell about Ed Henry,he was an irascible,old SOB who would have done a heck of a lot better if he would have adopted a kinder,gentler approach.IIRC,his wife was a nurse and brought home a steady paycheck which allowed D.E. Henry to pursue his knifemaking.
If I am disemminating any misinformation,somebody step up and set me straight.
I really like his knives and would love to acquire an example.
Yitz!? :D


Nick,
I don't think many were impressed with SK's posts and I'm not gonna' try and apologize for him,again.If a horse was ever beat any deader than that one,I haven't heard about it yet.
If you are interested I'd be happy to send one to you to play with,it will be a wood handled, small Spirit blade.
No iron sand,jewel steel mystery blade here, just a straight 1095 fighter styled knife, just send it back when you're done.Let me know.
Everyone else,
I'm not marketing or spamming for SK,just trying to give back something to this great place where I've learned quite a bit.

Doug
Click to expand...
LOL.......that is what I have heard and read too about Ed Henry. But with that said, a little while back, there was a debate of sorts in Blade about whether to put him in the Hall Of Fame. The issue was his personality and his dealings with potential customers. My thought was are you kidding?!?!?!?! Of COURSE he should be in the Hall Of Fame. Just look at his knives!!!! Sam kind of deal with Shiva. He seems to be a very talented knifemaker and also a very accomplished martial artist, but the bragadoccio and use of terminology like "flesh eater" strikes me as somewhat odd for a true martial artist.
 
jdm61 said:
LOL.......that is what I have heard and read too about Ed Henry. But with that said, a little while back, there was a debate of sorts in Blade about whether to put him in the Hall Of Fame. The issue was his personality and his dealings with potential customers. My thought was are you kidding?!?!?!?! Of COURSE he should be in the Hall Of Fame. Just look at his knives!!!! Sam kind of deal with Shiva. He seems to be a very talented knifemaker and also a very accomplished martial artist, but the bragadoccio and use of terminology like "flesh eater" strikes me as somewhat odd for a true martial artist.
Click to expand...
Joe,
I've already said too much and I'm 99% sure where this thread's headed,hope it don't but seen too many of them already.
If you wanna' give him a call,he's very personable,plus your an ex-soldier aren't you?
Ya'll will get along fine.

Doug
 
I think HT is the most important part of blade making (I include the thermal abuse suffered during forging as heat treat). That's why I send them out to be hardened in inert atmospheres and get -300 cryo and every one gets Rockwell tested.
 
Do collectors consider Heat Treating to be something they require a maker to do themself? Does a knife's value to a collector go down if they know that one of the chief processes has been farmed out to a third party, or are they happy that a maker does this? I want to get a sense of if customers want to "pay" for the costs of outsourcing heat treatment or if they are willing to "pay" knowing specifically that the maker himself did the heat treatment.
 
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