Flo_Evans said:
The original techniques where lost some time ago. Allot of "damascus" knives sold today are just different steel folded together then acid etched for appearance. They recently discovered (according to wikipedia at least) that real damascus steel has carbon nanotube structures in it. How the hell they where able to make carbon nanotubes in the 1500s is beyond me...
This is correct - the original Damascus steel is properly called
Wootz, while most 'Damascus' steel that is sold today should be described as
pattern-welded steel. Metallurgists have made strides in their attempts to recreate Wootz, but while most of the manufacturing techniques have been rediscovered, a lack of the special naturally-occurring iron ore has proved a major stumbling block.
Wootz was originally created in India around 300 BC. It was formed in a crucible from very specific iron ore mixed with charcoal and glass; and its production ceased when supplies of the unique ore dried up. It gained the nickname 'Damascus steel' because it became very popular in the Arab world. The Persians were renowned for using Wootz in the creation of fine swords, and were largely responsible for making the steel famous.
Wootz was prized for its ability to hold an edge whilst retaining toughness. When heat treating steel, one generally has to sacrifice one for the other: hard steel which holds an edge becomes brittle; tough steel which absorbs shock dulls quickly. Other cultures have dealt with this problem in different ways throughout history.
In Japan, exceptionally poor-quality raw materials lead to a highly complex process of refinement and hardening that created some of the most impressive sword blades in the world. Steel is folded repeatedly to remove impurities, and then the blade is differentially hardened. This allows the edge to retain sharpness, but the brittle steel is limited to the one area in which it is needed. The spine of the sword is left reasonably soft, and thus it absorbs shocks which might otherwise cause the blade to shatter. However the hard edges can be prone to chipping, which should then be polished out by a highly trained professional with a set of stones. The average samurai would probably have had some basic knowledge of polishing for use in the field; but the Japanese sword polisher was valued almost as highly as the smith, and he performed a vital role in the creation and proper maintenance of high-performance weaponry. This is still true today: it costs almost as much to have a Japanese sword correctly polished as it does to have it forged.
In the west, the Germanic tribes created pattern-welded steel. Rods of steel (and occasionally iron) containing different levels of carbon are welded together in parallel; then folded and twisted into a billet, which is then forged into a blade. This results in swords with soft, shock-absorbent cores and harder edges. The difference in hardness is less drastic than that of Japanese swords, so the edges dull more quickly. However they can be sharpened much more easily, and are less prone to chipping.
In the modern day, artisan bladesmiths make use of pattern-welding to create beautiful designs in their steel. When the steel is etched with acid, the hard steel darkens and becomes distinct to create contrasting patterns. With the right twists and folds, exceptionally complex designs are possible. However, contemporary heat treating techniques have rendered the functional qualities of pattern-welding redundant. The introduction of the blast-furnace in the 9th century caused the technique to die out almost completely - bladesmiths were finally able to create homogenous high carbon steel and they never looked back. These days, properly heat treated steel can be fine tuned via industrial processes to hold an edge while retaining shock resistance in a much less complex manner; though with regard to knives and swords, the best pattern-welded steel should offer equal performance to modern through-hardened steel in a blade.
The properties of Wootz, however, may be sufficiently unique to warrant its use alongside other modern steels; and it remains a curiosity to historians, artisans and engineers alike.
Here are some examples of the different types of non-homogenous steel. First of all, an image of true Wootz. The three images are taken from three antique blades, and each includes the mark of its respective maker. B and C are from two shamshirs, and A is from a knife made from a cut-down shamshir. C is pictured in full below.
Here is an example of a Japanese sword - made quite recently, in 1942, by master smith Tsukamoto Okimasa. The patterns in the steel (
hada) are revealed through polishing, and these images display both the subtle activities caused by forge-folding and the wavy line (
hamon) along the edge which signifies the harder steel.
This is a pattern-welded Viking sword made by the Czech bladesmith Patrick Bárta: a reproduction of a Norwegian sword made in 800 AD. The high-contrast patterned area which forms the shock-absorbing core denotes the most profound mixture of hard and soft steel: the acid etching darkens the hard steel and leaves the soft steel/iron areas light. The edges are more or less homogenous, but remain unetched. Note the subtle activities in the edge steel on either side of the core: they show the results of forge-folding similar to those seen on a Japanese sword.
Finally, this is an image displaying the cross-sections of several different types of ancient Germanic sword blades; all reproductions made by Patrick based on archaeological finds.
Check out his website for many more photos of his work, as well as walkthroughs which detail the processes of his craft.
The image details the evolution of European pattern-welding. From left to right: blade with a hard edge, blade with a soft iron core, sandwich blade, proto-pattern-welded blade, two pattern-welded blades; and finally a pattern-welded blade with a soft iron core.
