I find this to be a very interesting question, partly because it gives me a great opportunity to find out more about the person asking the question. This is because the very first step in answering it is to find out how the asker defines “performance”. The definition has changed greatly over the centuries, but even within a given region and time period it likely varied based on what characteristics the individual valued most.
Before I get into this further, for the purposes of this article I will be using the catch-all term “crucible steel” to refer to the broad array of different historical steels that fall into this category. Historical writings indicate that the discerning buyers of the time recognized that these steels had certain shared properties, but they were also aware of the fact that crucible steels from different regions had specific characteristics that might make them better or worse for specific uses. To use a modern example, 52100 might be a great steel for making a knife, but I would choose L6 or similar when making a sword. Also, even in modern times there are certain regions or specific companies that have very good reputations, while others are viewed with greater skepticism. I will be using the broader category of “crucible steels” because the question is typically directed at the broader category rather than at the products of a specific smith.
In the historical context, crucible steel blades were held in extremely high regard across a very broad region and over many centuries of history. I think this alone is a good enough reason to say that “yes, historical crucible steels were high performance materials.” Other options were always available, so if crucible steels were the preferred choice then we can assume that it was with good reason. It is reasonable to assume that performance varied, but that the overall average was considered to be better than the other options.
For clarity, in the historical context the other options basically boiled down to variations on bloomery materials. Here I am using “bloomery” to refer to all the materials that were produced by processing iron ore through a relatively small charcoal furnace. While different regions had slightly different furnaces and methods, the “blooms” that were produced were quite similar across the iron-producing regions of the world. I may get into the operation of bloomery furnaces in the future. The “blooms” produced by these small furnaces often had a range of carbon contents in different areas of the single mass, while also included in the mass was a substantial volume of entrapped slag. The blooms were then processed further, and the type and extent of further processing dictated the qualities of the end product. The evidence seems to indicate that in most regions where both materials were available, crucible steel blades were preferred over bloomery steel blades.
Next we move to the question of whether historical crucible steels would have been considered “high performance” by modern standards, and I think this is much trickier to answer. This is partly because our modern view of performance is much different than the historical view of performance. When the quality of the sword might become the difference between life and death the absolute most important quality is “will not break while using”. A sword that dulls with use can be resharpened, but a sword that breaks in use could easily be a death sentence. Modern buyers put far more value on hardness and edge retention, while durability was the single most important selling point in the days when swords were actually used in battle.
In modern times we have the luxury of not measuring our blades in terms of life or death, and as such we see greater focus on other aspects of performance. I think the three basic categories typically mentioned are as follows:
-Toughness: how well the blade is able to absorb abuse without taking permanent damage.
-Sharpness: how easily the edge cuts the target materials.
-Edge retention: how long that cutting ability lasts.
If we search the internet the vast majority of the information and opinions that are available will indicate that all of the above factors are driven primarily by chemistry, with a somewhat smaller portion of the information pushing the idea that the appropriate heat treat is similarly very important. I would not argue against these concepts for the simple reason that chemistry and appropriate heat treat are incredibly important, but I also think that there are additional factors that are very important for crucible steels that are largely being ignored. Primary among these is appropriate forging, which is of particularly large importance for the UHC (ultra high carbon) crucible steels that we are talking about today; improper forging of these steels can result in microstructures that simply can’t be fixed through heat treating, which is part of why the steel industry moved away from the UHC steels for such a long time.
In looking at modern crucible steels I see there as being three basic categories: 1) historical chemistries with very low Phosphorus levels, 2) historical chemistries with relatively high Phosphorus levels, and 3) steels with specific alloying to achieve particular outcomes. There are also crucible steels made by smiths who are essentially just making random alloys, but I don’t have much patience for that category because the outcomes will be so unpredictable; such steels will most likely underperform since achieving a good outcome is closely tied to knowing what is actually in the steel.
In future articles I will address each of these categories in greater depth, but for now I am going to speak in more general terms. It is my opinion, based on making crucible steels and blades from these steels for nearly 25 years, that steels from all three categories CAN be made into high-performance blades by modern standards…but that there are no guarantees of this outcome. If I make a sword from L6 or S7 I know that a good heat treat will result in a very good blade, but for the crucible steels the forging process that creates the blade is a key driver of the end performance. The process of making a good blade from a UHC crucible steel is much more of a “one way street” in the sense that it is much more difficult to go back and correct earlier mistakes. This is not to say that every step has to be carried out perfectly, but instead that the forging must be a more deliberate process that avoids a few key pitfalls.
I would also say that the high-P wootz category is the trickiest of these to pin down in terms of performance. When properly forged and heat treated the resulting blades can be incredibly tough, but also rather soft by modern standards. In my testing of the P-wootz materials it is common to have edge hardness levels in the low 50s HRC, which is perfectly acceptable by historical standards but considered very low by modern standards. The trade-off is that these blades are remarkably tough; in my testing I was able to bend a blade to 90 degrees and then hammer it straight again on the anvil…and I am still using this blade for general yard work. Because the edge is relatively soft it needs to be sharpened a bit more often, but there is essentially zero chance of it chipping even if I hit a rock or steel fence wire. One caveat to this is that I have not tested the P-wootz blades in colder environments; my testing was done at roughly 70f/21c, and high-P steels theoretically suffer from higher brittleness at temperatures below roughly 45f/7c. Future testing may reveal whether P-wootz blades suffer from this cold weather embrittlement even if heat treated to be incredibly tough at warmer temperatures.
If you visit my YouTube channel you can watch a number of the testing videos that I have made. These are all on my own steel so I don’t want to imply that these are universally applicable. There is a tendency to just call everything “wootz” and then pretend that a single test piece applies to all steels in that category. Not only is this lazy reasoning, it is simply bad science. Having said that, I think that testing of modern crucible steels can tell us a great deal about the strengths and weaknesses of historical crucible steels, but only if the testing is designed properly. The blades being tested should match the historical blades as closely as possible in terms of chemistry and microstructure, and the testing itself should reflect realistic use rather than idealized criteria. It is also important that we look at the blade design itself; the historical smiths knew the strengths and weaknesses of the materials they used and did their best to design accordingly.
I realize that all of this is sort of side-stepping the actual question: are either historical or modern wootz high-performance steels? If we instead ask whether these are better steels than, for example, S7, L6, or 6150, then I would have to say “no”; all three of these choices can be heat treated to be tougher while at the same time being more resistant to permanent deformation…toughness through springiness rather than toughness through being more ductile. This is less a comment about wootz and more a comment about just how far steel metallurgy and steelmaking have come in the past two centuries. To add some context to this, the same holds true for all of the historical swords and sword steels, including the much-storied katana. As a blanket statement, the historical steels simply can’t compete with the modern steels when we get into the extremes of performance.
That last statement actually brings us to the crux of the issue: should we define performance by the extremes of use or should we instead use a more realistic measure? Ignoring any real numbers here, if 6150 can withstand 50x and wootz can only withstand 25x, does this really matter if the sword will only ever face 15x? By the numbers the 6150 is clearly better than the wootz, but in actual use this extra performance might never come into play. This is like the question of whether a Ferrari is actually high-performance when it is only driven in New York City. I think the useful definition of performance is related to the actual conditions a blade will face versus comparing the theoretical limits of the material. The theoretical limits are academically interesting, but in many cases have little or no bearing on performance in the real world.
In the end, each of us has a slightly different definition of performance, because we each value different characteristics more highly. This is a conversation that I often have with my customers at the beginning of a new project because it is important to me that I understand the intended use and expectations. The design and materials need to be specific to the end use or else the results will not be good. In the historical period this was known by both smiths and buyers, but in the modern period it is not as widely understood.
A good example of this is a sword that I made for use (by me) on the TV show “Knife or Death”. This was, unfortunately, a short-lived program due to some flaws in the design of the show, but it was an amazing study in how different blades (and users) held up to extreme usage. Perhaps the most brutal obstacle in the course was a large block of ice that needed to be chopped in half. This ice block destroyed a number of blades, including at least one rather nice katana, because it represented a type of target that would have been outside the expected range for most blades, especially swords: a very hard, immovable object. I competed in the second season of the show, so I was able to design my sword with foreknowledge that it would be facing at least one type of extreme target; my sword chopped through the ice block easily and with zero damage! Unfortunately my lack of skill as a sword user kept me from completing the obstacle course, but this still stands as a good example of how a swordsmith, whether modern or historical, can design based on the expected usage.
It is also worth considering that in the historical period there was a much closer interplay between the sword user, the swordsmith, and the expected defenses of the opponent. There was a constant evolution of armor, shields, sword designs, and materials science that created a continuous flux in all of these areas. As such it is reasonable to assume that the sword user would have been keenly aware of what the sword was designed for and would not try to, for example, chop down trees just to see whether the sword could do it; this cannot be said of the modern sword buyer. It doesn’t take much searching on the internet to find examples of swords being used against targets that aren’t appropriate to the sword design; if the sword fails in this case does it actually reflect on the performance of the steel?
As we can see, “performance” is a very tricky term to pin down, so it is no surprise that “high performance” would be even trickier. It seems reasonable to me to define “performance” as “the ability to perform the expected duties without premature failure in one of the key measures”. In the case of swords I think this essentially means that the sword can survive a battle without being damaged in ways that reduce its functionality in the next battle. This illustrates why it was generally preferred that the edge dulled rather than chipped, since a chipped blade has had both its cutting ability and its structural integrity partially compromised. In this scenario a “high performance” sword would not only survive each battle but would require noticeably less refurbishment in the form of straightening the blade or sharpening the edge. Wootz blades were renowned for this type of performance.
In summary, I believe that both modern and historical wootz materials could be considered “high performance” based on both historical and modern definitions of performance…with the caveat that both modern and historical wootz are far more dependent on the forging stage for their characteristics (versus modern commercial steels) and therefore are likely more variable in their actual performance. I think that rigorous performance testing is of great value, but it is important to remember the following: scientific testing can tell us the stress levels that will cause a steel to fail, but only use testing can define the stress levels that a particular weapon would actually face.
If you have any questions or comments please email them to me directly. I have a very busy schedule so I can’t devote time to dealing with Spam comments and Trolls on my blog posts. I do want to hear feedback from actual readers, but I don’t have time or patience for Bots. -Peter