Damascus hardness question

B

Bill Bryant

Joined
Mar 19, 1999
Messages
54
I would like to make a couple knives with damascus and have a question. A guy approached me at a recent gun & knife show to show me his damascus. It's made of L6 & 1095. Not knowing anything about working with damascus I asked how hard he got it. He told me he hardened his to about 60 Rc. I told a friend of mine who's been making knives full time for many years that and he says no way, damascus can't get that hard. Which is it? Can damascus be hardened to 60 Rc? If it can but not with those two steels, which combination(s) will get that hard and who makes it? Thanks in advance for your help.

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Bill
"There's nothing friendlier than a wet dog"
"The more people I meet the more I like my dogs"
 
Tell your friend to get a knife from Jean José Tritz from Hamburg made with one of his LD-blades (LD = Leistungsdamast = performance damascus). These are normally capable of scratching glass AFTER tempering, which means about 62 HRc. Made of file steel (1.2008, 1,4% C) and roller bearing (1.3505, 1,05 % C). There is no big problem of getting it that hard if you use the right steels from the start.

Achim
 
If your using materials that will achieve Rc 60, when starting, you have a chance of getting that much hardness. L-6 and 1095 to Rc 60? I think not. 1095 will get there, but L-6 is questionable. Especially after several welding heats.
For most forgable steels, Rc 60 is a bit higher than I would like to see in a using blade. Obviously when combining two different materials, you going to get different Rc levels from each. Most bladesmiths who know and understand what they are dealing with would not give you a single Rc hardness on damascus. As an example, I use 1084 and 15N20 for the majority of my damascus, and the Rc is usually a 57-59 range. High hardness, in and of itself is not a good indicator of the using quality of a blade, there are too many other aspects that go into a high performance knife.

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Ed Caffrey "The Montana Bladesmith"
ABS Mastersmith
www.caffreyknives.com
 
They've tested the blades of Tritz down to the layers and due to carbomigration during welding the carbon content in the layers, thus the hardness level, was the same overall. The problem with the steels that have a high nickel content is that the nickel will make carbomigration impossible. So Ed is right if he sais that a damascus blade made from 1084 and 15N20 will not have a homogenous HRc level due to the high nickel content in the 15N20.

Achim
 
Well, having spent some time in the lab on this particular issue, I'm gonna be a spoilsport and disagree with everyone a little bit.

Achim is right about Tritz, he showed me the sharpest knife I have ever handled made from pattern welded steel. He and his buddy Roman are both into it in a very serious way, and they do nice work that is very much "performance first".

The 15n20 is not all that high in nickel, and it is definitely not high enough to stop carbon diffusion. Slow the rate a little bit, perhaps, but I doubt that even.

Depending on the conditions the material was welded up in (forge atmosphere and shop practice details) there might be some carbon loss in process making steel from 1095/15n20, but it is relatively insignificant most of the time, and the resulting steel *should be* at least .75C in total when done, probably a bit more. That is plenty to hit HRC 60 as quenched. Quench severity and shop practice will also play a role here as well. Mar quenching is safer, but there is a slight sacrifice in as quenched hardness (not really an issue, IMO). For all there is full hard as quenched, nothing beats water as a quenching media, but it is dangerous sometimes (things can crack). I have been using a solution of aqueous polymer for quenching some of the low hardenability steels, and find it very nice. Faster than oil, doesn't stink up the shop like oil, safer than water, and washes off with water when you're done. The one I am using is called "aqua quench 3600" fgrom Houghton. It is a chemical called polyethyloxazoline (PEO), and has slightly different characteristics from the much more common polyalkalynglycol (PAG), which is rapidly replacing oil quenching in industry due to it's much "friendlier" nature top the operators, equipment, and environment".

Much of what is being made today in pattern welded steel will get plenty hard to make a really great knife from. This was not always so.

There is a lot to this equation. Steel component selection, shop practice, then the heat treating practice. All of those things are important.

L-6 and 1095, depending on proportions and shop practice, can most definitely hit HRC 60 as quenched. L-6 and 15n20 are not the same thing, though they are somewhat similar, and give similar results in pattern welded steels for appearance, but not heat treatment. L-6 has Cr, Mo, and Ni. 15n20 has only Ni of those three. The Cr and Mo play a much larger role in the steels heat treatment behavour than does the nickel, especially in combination with nickel also. L-6 should really be called 4370, but it is not.
 
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