(When) Will It Blend?

A

Atemporal

Joined
Aug 4, 2012
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--I'll preface this by saying I am not a maker, and am merely interested in the technical aspect of knifemaking. I want to get as much technical knowledge beforehand as possible so that I just have to work on skill and equipment. Both of those things are hard enough as it is, and get even harder if you are constantly trying to flip back and fourth to a book to figure out what the heck to do next. Whenever I actually get myself a forge I'll start with a nice easy bar of 1084 and go from there. I just enjoy discussion about impractical ways to improve performance.--

So with the disclaimer out of the way, I have a question about damascus (pattern welded) steel. Say you take one of the well known blends like O1/L6 and you want to make a good chopper out of it. O1 is a hard, high-carbon steel, and L6 is a tough lower carbon steel. Ideally, neither one should make up the edge of your blade alone, as it is the balance of those properties that you are after. The obvious is to fold the steel more, to make a finer layer structure of the two steels.

How far can this process go? I have heard about carbon migration between steels in finely folded damascus, but can you actually get it to the point of blending the steels?

A number of thing aught to happen as the steel is folded more and more in (I think, please correct me) this order:

1. carbon content begins to equalize between the steels
2. visible layers disappear
3. carbon content reaches equilibrium
4. alloying elements begin to be evenly mixed
5. homogenous steel

Is this correct? Could you eventually get to a point where the steel is as if you had melted both and mixed? Would the properties of the result be an average of the starting ingredients or could they be completely different?

I am interested to know about both the metallurgical aspects of this process, and to hear if anone here has experimented with really high layer count damascus, say, <1000 layers. Thoughts? Stories? Is it a waste of time, even if its just for fun?
 
I'm not a big pweld guy just now, but I have done some and have some input to start with. O1/L6 is a mix that works since they both respond to heat treat in a similar fashion, and the nickel content of the L6 creates a contrast with the darker color of the O1 when etched. The result should be a blade with nearly the cutting ability of 01 and nearly the toughness of L6. The more heats and longer soaks used to work the billet will increase carbon migration and decarburization- so the more the steel is folded, gradually it will begin to lose carbon content and contrast. Bright lines resulting from the L6 will grow smaller and less visible as layer count increases. Upwards of 1000 layers will be a pretty fine pattern- many of the bolder patterns you see will be somewhere from 200 to 600 layers for good contrast. Some bold patterns like "twisted nickel" use 20-90 layers for very high contrast.

You can reach a point where the steels are for all practical purposes homogenous; Japanese tamahagane blades are an example of this. This was often done more when steels needed to be homogenized to an even carbon content from a bloom of varying carbon content.

Modern damascus steels are aesthetic in nature more than anything now; the need to create an evenly heat treatable steel no longer exists with modern alloys, and the focus has shifted to using two high carbon alloys of differing appearances when etched to create contrast and visual interest.
 
Thank you for the thoughtful reply. I was trying to figure out if you -can- well before I tackle whether or not you -should-
 
You can make an excellent knife with 1084 steel even before you get a forge. Stock-removal works fine on "plain" steels as well as highly-alloyed ones. :)

As for pattern-welding to achieve a great, homogenous blade steel - that's simply not necessary these days. I'm sure you could do it, but remember you're not going to make the billet any better metallurgically than either of the bars was to begin with, and stand a pretty fair chance of making it much worse if there's any over-heating or bad welds at any step along the way.

Honestly, you're trying to solve a problem that doesn't exist. But if you want to do it just for fun and have the results tested, then no it's not a waste of time.
 
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At the moment its a just for fun thought-experiment, which may one day turn into a just for fun project. I just got inspired reading a certain thread about really high layer count damascus. I wondered if it just got smoother, or if you could actually over do it.
 
Carbon migration happens pretty quickly, especially at welding heats. I would be surprised if there is much variation in carbon content across a pattern welded blade with more than a just a couple heats on it.
 
I am thinking that you are correct. But add you will loose carbon and alloying elements to oxidation. So my guess is the caracteristics that you look for in your steel will diminish as the number of folds increase beyound a certain point. i.e. scandanavian laminates are usually 3 layers. If there was an advantage to be gained by having 5,7,9 etc, then the laminate would probably have more layers.
 
As far as a forge btw, all you really need to start is a pipe, a hair drier (cold setting) and a hole in the ground to have a "pot" for the pipe opening to come out of (tuyere). That and a little bbq grate to put over top maybe.. and regular hardwood charcoal (not briquettes). There are fancier ways to do it, but really its just charcoal and an air supply. For an anvil you can get a solid square piece of steel from a scrapyard or something, if there are none at garage sales etc. You could use coal too, both have pros and cons.. but I like the smell of charcoal.
 
I wondered this when I was watching Highlander with my sons a couple months ago. At 76 folds, you have 8×10^23 layers. In one mole of iron(about 2 oz.), there are only 6.022×10^23 atoms. I'd guess somewhere around 30 folds you start getting more theoretical layers than atoms wide. At only 16 folds, you talking 65536 layers, which you would need a microscope to determine.

BTW, the answer is: at 81 folds you have more layers than atoms in a 4 lb. Toleda Salamunga folded 200 times.
 
Atemporal said:
--I'll preface this by saying I am not a maker, and am merely interested in the technical aspect of knifemaking. I want to get as much technical knowledge beforehand as possible so that I just have to work on skill and equipment. Both of those things are hard enough as it is, and get even harder if you are constantly trying to flip back and fourth to a book to figure out what the heck to do next. Whenever I actually get myself a forge I'll start with a nice easy bar of 1084 and go from there. I just enjoy discussion about impractical ways to improve performance.--

So with the disclaimer out of the way, I have a question about damascus (pattern welded) steel. Say you take one of the well known blends like O1/L6 and you want to make a good chopper out of it. O1 is a hard, high-carbon steel, and L6 is a tough lower carbon steel. Ideally, neither one should make up the edge of your blade alone, as it is the balance of those properties that you are after. The obvious is to fold the steel more, to make a finer layer structure of the two steels.

How far can this process go? I have heard about carbon migration between steels in finely folded damascus, but can you actually get it to the point of blending the steels?

A number of thing aught to happen as the steel is folded more and more in (I think, please correct me) this order:

1. carbon content begins to equalize between the steels
2. visible layers disappear
3. carbon content reaches equilibrium
4. alloying elements begin to be evenly mixed
5. homogenous steel

Is this correct? Could you eventually get to a point where the steel is as if you had melted both and mixed? Would the properties of the result be an average of the starting ingredients or could they be completely different?

I am interested to know about both the metallurgical aspects of this process, and to hear if anone here has experimented with really high layer count damascus, say, <1000 layers. Thoughts? Stories? Is it a waste of time, even if its just for fun?
Click to expand...

Look closely at any Nihonto for the answers you seek.
 
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