Can A Watch Case Be Made Out Of Damascus Steel?
Damascus steel knives have a long history. They date back to 500 AD and have a significant place in history. All you need to do is look in any museum that holds a sword collection to confirm this. What do these knives and swords of history have in common with watches? I thought there was very little until a friend of mine started to wax lyrically about a new knife he had just purchased:
“It is not just that Damascus steel is perfect for knives; it also requires a specific production process that enhances the knife’s flexibility and strength. These characteristics allow the steel to hold an excellent edge, be remarkably tough, and exhibit a water-like pattern on the knife’s surface. This decoration is not merely a surface decoration; it is integral to the performance of the steel and permeates the full thickness of the steel.”
He also happens to be a keen watch collector, so I suggested he may like a Damascus steel watch case, which he jumped at. At the end of the conversation, I had that sinking sensation that my suggestion may have been a bit rash. If you have been following this series of posts on the stainless steels used in making watches, you will realize that steels for knives and steels for watches are entirely different in their physical properties. Watch steels tend to be softer, malleable, and low carbon, so they can be shaped and machined easily and accurately. Steel for knives is hard, tough, and above all, high carbon, so they can hold a sharp edge. This was going to take some effort to work out if it is even possible to create a watch case out of steel that is exclusively used for knives.
History of Damascus Steel
To start with, I needed to find out what Damascus steel actually is and how it is created. It became famous in the crusades because the Turks turned up to battle with swords that were infinitely superior to the invaders. These blades were characterized as sharper and tougher (they can bend without snapping) than those of their opponents and had attractive surface patterns on the blades. Historically these blades were made from special steel called wootz steel, found in India. A second method has been developed through a process called pattern welding.
Creating A Modern Damascus Steel Blade
Pattern welded Damascus steel is created by forging alternate sheets of high carbon and low carbon steel together and then continue working them through a series of stamping and metalworking processes that create many layers. This process allows the various layers of the different steels to be revealed at different points on the knife’s surface, which are then revealed when the blade is etched, thus creating the damascene pattern.
How Damascus Steel Was Created Historically
The second process for creating a Damascus blade is the original methodology and requires a lot more work and particular alloying materials. This is the original method for creating the damascene pattern on a blade and is typically viewed as the most authentic process in historical terms. The blades were forged from a single piece of wootz steel, the process that the farrier would have followed allowed for the carbon to diffuse through the crystal structure of the steel and accumulate in specific locations to allow alternate layers of high carbon and low carbon steel to develop within the steel blade. These fine layers were then visually enhanced by etching the blade’s surface, but as with the pattern-welded steel, the structure of high carbon and low carbon areas permeates the blade’s full thickness.
Blade Versus Watch Case
When we looked at the details of austenitic steels used for making watch cases, they are low carbon, which makes them softer and more ductile (more likely to bend and remain deformed). On the other hand, a good knife blade needs to be tough – this means it will bend without snapping but spring back into its original shape. A good blade also needs to remain sharp or hold a good edge, requiring hard steel.
Steel is an alloy of iron and carbon, and as the proportion of carbon increases in the steel, it becomes progressively harder. This explains why knives are made from high carbon steel. The hardness allows a very fine, sharp knife-edge to be developed and remain as the edge is used. But there is a compromise that needs to be struck because too much carbon will cause the steel to be brittle. If the knife blade is too brittle, it will easily shatter, so a degree of toughness needs to be introduced into the blade.
Defining Feature of Damascus Steel
Steels generally have a carbon content between 0.03% and 1.7% carbon, with alloys with less than 0.03% carbon referred to as pure iron and those above 1.7% called cast iron. The amazing thing about the wootz steel is that it has a carbon content of 1.57%, which is incredibly high carbon content for any steel, yet it remains tough. As a reference, a modern high carbon stainless steel knife would typically have approximately 1% carbon. This difference is huge.
Ancient Damascus Steel – Into the Details
It is not clear that the ancient sword makers knew why they created such great swords. The skill can be documented from 500AD, but after 1850 the skill appears to have been lost. After the second world war, a significant scientific effort was put into understanding Damascus steel’s microstructure and how to recreate it through ancient methods. This has resulted in a thorough understanding of the processes to recreate the damascene pattern plus a model to understand the atomic processes that result in the distinctive pattern.
As with all steel, it is the carbon and how it formulates with iron at an atomic level that dictates the final steel properties. As I have alluded to earlier, the process is very complex, not fully understood, but for our purposes, it can be explained as follows.
The Atomic Movements
The wootz steel has one very particular element present in tiny quantities, Vanadium (V). Vanadium can form vanadium carbide with the carbon held within the steel lattice. This is exactly the same when iron (Fe) reacts with the carbon to form iron carbide (Fe3C) or cementite. The key aspect here is that as the blade is heated up and worked (forged) over many cycles, the cementite will develop as the workpiece cools. A portion will dissolve back into iron and carbon in the lattice (austenite) as it is heated back up.
When vanadium carbide forms within the crystal structure, it is more stable at higher temperatures and does not dissolve back into the crustal structure as it is heated. These areas become a point of attraction for these carbides to form and accumulate. As the number of forging cycles increases, the carbide layers’ thickness increases and eventually becomes visible. The difference between the cementite layer and the majority of the remaining steel structure creates a distinctive damascene pattern.
Damascus Steel Performance
So how does this process create such high-performance knife steel? It is useful to compare the pattern welded Damascus steel and the wootz steel forged version. They reach the same result but from different starting points. With wootz steel, the layers of high carbon steel and lower carbon steel are created by the different atomic layers’ growth by the diffusion of carbon in the crystal lattice. In the pattern welded process, the layers are created at a macro level and then thinned to the atomic level through the forging and shaping process.
Why is this so important? I am sure that the swordsmiths that created the Damascus sword had no idea, but they had created a composite material that blended the physical properties of two materials to make a third. The cementite (carbide) layer is extremely hard and therefore excellent for holding an edge and remaining sharp. The rest of the steel is more ductile, but the two together result in a tough blade that remains extremely sharp.
Back to Watches
I wrote a whole blog on the need for austenitic stainless steel to make watch cases, but now I am trying to make a watch case from knife steel! You are probably scratching your head and thinking that there is no way a watch case can be made from Damascus steel. That is certainly true if we start from the original wootz steel. The trick here is that we are only looking to re-create the damascene pattern on the watch case. The physical properties that are so important in the sword are irrelevant for a watch case. In fact, they are detrimental to making a good watch case. What is important is that the layering of high carbon steel and low carbon steel is achieved so that it may be etched to create the damascene pattern.
One further key point is that a watch case needs to be made from stainless steel. Everything we have discussed so far has been exclusively concerning steel, so a Damascus steel blade will corrode if it is not maintained carefully. The flexibility of working with stainless steel affords us a great deal more flexibility as the material properties can be “tweaked’ with additional alloying elements.
The Magician’s Slight Of Hand
So how can it be achieved? The wonders of modern material science have bestowed us with a process called powder metallurgy. This means that high carbon stainless steel and low carbon stainless steel can be fused together in very fine patterns to recreate a damascene pattern (you can even choose the pattern!). Another wonder of this modern understanding is that it can be done with austenitic stainless steel. This will allow the watch case maker to create a precision watch case that shows a distinctive damascene pattern.
The one thing I know for sure is that a damascene watch case will look amazing. So, anyone for a damascene watch? Let me know below.