Cheyenne,

In my experience,you can get pretty good performance from the mix if at least 75% of the billet is 0-1. Watch the high temps with o-1, it doesn't like overheating at all(avoid white range). If that's all you have available, why not. I never got much of a pattern contrast with the combo. Much better with L-6. Have fun, Dan

Dan,

I remember Moran saying he used one piece of O1 to two of mild steel. That produced a tough blade but not one that really held a great edge. At that time, we did not really understand the process of carbon migration in the bladesmith community so some combination of the two steels seemed reasonable. Today we have to recognize that carbon migration occurs pretty quickly at weld temperatures and after a few welds we have a somewhat homogenous steel as far as carbon is concerned. So from a functional perspective, if I had a steel with a carbon content of .8 and weld it to a piece of steel of the same size that has .1 C, then my resulting billet after x number of welds is going to be between .4 to .5 Carbon. If I weld two pieces of the .8 C steel to one piece of the .1 C steel (mild steel), I would eventually after a few welds have billet of around .6 C. The use of mild steel in combination with O1 is a question of how much carbon do you want in the billet to make a working knife? What proportions of each steel will get to that desired goal. If you want a blade with really good edge holding then you may want a blade with .8 C or higher. On the other hand you may settle for .6 C. So you have to do the simple math and figure out how many pieces (you could use thicker pieces of O1) of O1 do you need in relation to the pieces of mild steel.

A lot of smiths have gone to using two steels where both kinds of steel have a high carbon content. For example, O1 and some variant of L6 will both have carbon levels high enough that the end result even after carbon migration is still about .75 or so. If you want a higher carbon content then use 1095 with O1 and you end up with something around .85 or so depending the ratio of the two steels to each other.

The other aspect of damascus is the esthetics of the pattern. How bright or dramatic do you want the pattern. The more contrast in alloy content (chromium or nickel) in one of the steels the more contrast you get after the heat treat and etch. Also, different steels have different shades of gray when heat treated.

However, you seemed to be asking a question about performance. The answer to that question is related to a number of factors but the primary ingredient is carbon.

Dan Petersen

And excellent and informative post Dan.

Back in 2005 I was involved in a pretty in-depth study of the performance and characteristics of many of the popular damascus mixtures- 1084/15n20, pure nickel/1095, O1/L6, cable, O1/1018 etc… it was VERY eye opening and raised questions I am still looking for answers to today. All heat treating was done via salt bath austenitizing with temperatures and appropriate quenches to maximize the results for the given mixture. Samples were tested to discover maximum obtainable Rockwell values and corresponding drop in tempering. Things like consistency of hardening and levels of distortion were recorded. Microscopy was used to record the edge characteristics as sharpened and then at subsequent steps after cutting various mediums. A special apparatus was used that provided a standard cutting stroke at 10 lbs. of downward pressure. Finally impact testing was done to determine toughness. I still have the samples but have not had the time to do full metallography on the internal structures of the samples, and they are now buried under piles of other samples I haven’t had time for.

It should come as no surprise that the mixes which incorporated materials of all higher carbon hardened the best and displayed the most strength and abrasion resistance in cutting. Although there were differences in “how” the mixes cut and how the edge degraded. Things like cable and pure nickel mixes ripped through rope and paper like a laser even after several cuts, but were stopped dead by hard cardboard or wood. The microscope revealed that as they cut the weaker portions of the edge were torn out in use creating a saw tooth effect that was rather aggressive on soft targets but would simply smooth over on more substantial mediums. The top two cutters were O1/L6 and 1084/15n20, while not really exceeding others in one medium they held up the best on all mediums.

Rockwell testing was interesting. We destroyed the idea once and for all that “damascus” cannot be Rockwelled. What should be said is that certain damascus cannot be Rockwelled; the 15n20/1084 and the O1/L6 Rockwelled as consistently and accurately as any mono-steel sample. The cable, pure nickel mix and the O1/1018 were either all over the map or not readable.

The O1/1018 mix was the classic 1/3 O1 to 2/3 1018 mix and was problematic for the test because it required mixes of water, brine and detergent surfactants just to reach the mid 50’s HRC, this made the distortion issues out of line with the other samples. Almost any level of tempering dropped it to the low 50’s. Because of this, and a few other factors, the O1/1018 mix was included in subsequent tests but had to be excluded from the final results as there was no way to objectively compare them. A 52HRC edge is going to smooth over in short order compared to 59HRC, and it did. The one area where the O1/1018 mix did show greater values was impact toughness, but it required a heavier Charpy V notch since it tended to fold up instead of breaking on impact, and being at least seven points different in hardness it is just expected to absorb more foot pounds so these results were not used in the end either.

We work with the information that is available to us. Early on, modern smiths working with information taken for very old blades deduced that pattern welding relied on alternating layers of iron and steel. And this is true, to some extent, when you study old pattern welded swords, but these blades were made up of thicker iron and steel components which were welded up fairly quickly. There were also contributing factors of elements like phosphorus and silicon slowing the carbon diffusion. We can still get this today if we go with very coarse layers and get it done in just a couple of heats, but the folding and welding process of most of our damascus making will equalize the carbon content very quickly. The Japanese knew this and that is why they folded the steel to homogenize it. We now have the insight and information to realize that functionally there is no advantage to adding low carbon material to the damascus mix, unless you have a problematically high carbon content, as all it is doing is watering down the higher carbon content. What it does visually is still up for debate though.

Thanks guys for all of the information. Since the O-1/1018 mix only works out to 52HRC, I will probably pass on it then. To do all the welds by hammer & anvil and only be able to get the blade to 52 seem a lot of work for less than desirable results.