Sharpness of Damascus?

P

PCL

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May 25, 2012
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I have recently read the way a damascus blade was made by the French in the 1700's. It is written that after combining the steel and iron they added a steel insert to make the edge. Seems like san mai to me but I have no idea who started it. My question is, without the insert of a good steel for the edge how can modern damascus have a consistent sharp edge with lower carbon steels combined with the higher carbon steels and being forge welded together wouldn't some of the lower carbon steel be on the edge? Or is that what is done today?
 
Wondering this same thing the other day. If a damascus blade is, say 1095 and 15n20, you have half .95% carbon, and half .75% carbon. So, if in grinding the bevel and then secondary gives you an edge with some areas .95 and some .75.......would the edge be "up to par" with a mono 1095? This is probably a little subjective, I don't know. Good question that I'm really looking forward to the answers given by those who know what they're talking about, unlike myself. Edit....I say "half 1095 and half 15n20". I realize that damascus isn't necessarilly "half and half".
 
After welding a few times, the carbon migrates and moderates with its self. Meaning, a blade of several hundred layers of 1095 and 15n20 would turn into apprx 1080. Some gets lost from decarb. That's my understanding of it all.
 
From my understanding 1080 can be can be used for an effetive blade, but wont be as good as basic 1095. I hope it does'nt just come down to looks. The older French way or san mai seems better, you get the strength and flexibiity of the damascus and the cutting edge from the high carbon insert. I am a novice but that seems common sense.
 
I think that if all is done right, you will end up with almost as good of steel as when you started, but not better. I don't think that many would be able to tell the difference in 1080 and 1095, though theoretically 1095 would hold an edge better. 1080 would be tougher, and is easier to HT. With all the steels we have now, the only reason for Damascus is to look cool. I love Damascus, life is to short to carry an ugly knife, but I don't have any wild ideas that It is as super cutting ability, but it will do everything I need it to, day in and day out.
JMHO
Cody
 
One thing that gets left out of the discussion is the "Damascus Effect". This is a micro-serration effect of the edge caused by the layers. It makes an aggressive cutting edge for some tasks, but less proficient for others. This is one reason for having 500 layers or more. Below that, the effect is greater, and can be a problem. A good Damascus blade will cut meat and rope very well, but won't slice paper or fish as well. This is not to say that damascus won't get screaming sharp and won't cut paper....just less efficiently than a mono-steel blade of the same geometry.

As to the final carbon content, it doesn't really matter as long as both are eutectoid or higher. Either 1095 or 1080 and 15N20 make a superb Damascus. Properly hardened it would take a laboratory to tell the 1095/15N20 blade form the 1080/15N20 blade. I guarantee that you could not tell by the cutting ability.
 
Hi PCL,
Thank You for asking the Question.
Hi Stacy,
I am really glade you posted on this because you put it into words that I could understand..
Sincerely,
Dave
 
Damascus isn't made solely from high/low carbon steels anymore. Damascus isn't stronger or more flexible than the steels used in it's construction. Having owned and used only 2 damascus/pattern welded blades, my experience with them is limited. However, I am quite skeptical of the damascus cutting effect.
 
Good damascus is made up of two steels with very similar heat treat characteristics, so that the final result will be minimal variation in hrc between the bright steel and the dark steel (maybe 1 or 2 Rockwell points). The reason why Indian & Pakistani damascus is often derided is because sometimes it's not made from what they say it's made from, or it's made from mild steel and something with a nickel content. This can mean that there's a huge variation in hardness between the bright and dark steels. Or the steel may not be hardenable at all. In either case, rather than just using the damascus for fittings (or throwing it away), it can still make a decorative but functional blade, by using it for the cheeks of a San Mai laminate. Also, if the carbon content is the same or very similar, there will be little or no carbon migration. (It's a similar process to Osmosis)
 
Stacy, in your opinion, is there a Damascus effect when welding two high carbon steels together the same as high and low carbon steel? Or is it that the low carbon wear away faster then the HC. (but if the carbon has evened out, there wouldnt be high and low carbon, just medium carbon steel, which would wear at the same rate. Confused) I guess what I'm asking, is if the steel has become homogenous, where does this Damascus effect come from. Looking at the edge under a microscope would tell me that, maybe.
Jim Hrisoulas talks about the cutting ability of different patterns of Damascus, but doesnt get into the specifics of it.
Thanks
Cody
 
Hi Cody,
There can still be variations in hardness and wear resistance due to alloying elements other than carbon. Many of these are much less mobile than the carbon, and tend to stay put in the layer they started in. Hope that helps.
 
Very interesting and getting beyond my depth, lol. So with more layers 500 I believe was stated you would get more micro serrations assisting in the ability to cut correct? And in the layering process with the proper and planned similar HT qualities of the metals used you are aiming for consistent results. Then to me the proper HT and tempering is what will define the blade and it's capabilities. Believe me I am a novice but I try to pay attention to what I'm interested in, and I love the quality and looks of damascus. I guess another question would be if you had to bet the farm on a damascus blade would you san mai or not?
 
Steveomiller pretty well hit the situation. The two metals may have the same carbon content ( or the diffusion may make it equal), but the alloys are almost always different. When 1084 and 15N20 are welded together and folded enough to get 500+ layers, the blade will still have about .80% carbon, buy alternating layers will have different hardness and nickel content. That will make one set of layers wear away in buffing and polishing just a tad more than the others. That will in effect be a micro-serrated edge. This is what the "Damascus Effect" is. I believe it will be more pronounced when W2/1095 are used with lower carbon and higher alloy steels like 15N20/5160/O-1.

Much of the high contrast damascus made has layers of pure nickel in it. Some has 203-E ( 0% carbon and 1.5% nickel). These blends cause a nickel barrier between the carbon layers, and prevent any diffusion ( carbon can't cross a nickel barrier). Thus the relatively very soft nickel wears away at a much greater rate than the hardened steel, and really creates a toothy edge. Many folks don't like the feel of cutting of this edge, or its poor edge retention. If the layer count is high enough it is acceptable, but will never match a mix of carbon steels without the nickel.

For anyone who misunderstood my first post, there is no magic or advantage to the "damascus effect". It is what it is.
 
Thanks Bladesmith and stevomiller, good explanations, I was thinking a little 1d in a 3d world. There's more to steel then iron and carbon. Well, some steel!

Cody
 
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