Ill start it off with some basic info that I found on Wiki. I will have more info when my books arrive and I have a chance to read them. I also ordered a DVD. After I've read/watch the material I will let everyone know which materials are worth the time/money.
From Wiki:
Japanese swordsmithing is the labour-intensive bladesmithing process developed in Japan for forging traditionally made bladed weapons (nihonto) including katana, wakizashi, tantō, yari, naginata, nagamaki, tachi, uchigatana, nodachi, ōdachi, kodachi, and ya (arrow).
Japanese sword blades were often forged with different profiles, different blade thicknesses, and varying amounts of grind. Wakizashi and tantō were not simply scaled-down katana; they were often forged without ridge (hira-zukuri) or other such forms which were very rare on katana.
Steel production
The steel used is known as tamahagane (玉鋼:たまはがね?), or "jewel steel" (tama - ball or jewel, hagane - steel). Tamahagane is produced from iron sand, a source of iron ore, and mainly used to make Samurai swords, such as the katana, and some tools.
The smelting process used is different from the modern mass production of steel. A clay vessel about 4 ft tall, 12 ft long, and 4 ft wide is constructed. This is known as a tatara. After the clay tub has set, it is fired until dry. A charcoal fire is started from soft pine charcoal. Then the smelter will wait for the fire to reach the correct temperature. At that point he will direct the addition of iron sand known as satetsu. This will be layered in with more charcoal and more iron sand over the next 72 hours. Four or five people need to constantly work on this process. It takes about a week to build the tatara and complete the iron conversion to steel. The steel is not allowed to become fully molten, and this allows both high and low carbon material to be created and separated once cooled. When complete, the Tatara is broken to remove the steel bloom, known as a kera. At the end of the process the tatara will have consumed about 10 short tons (9.1 t) of satetsu and 12 short tons (11 t) of charcoal leaving about 2.5 short tons (2.3 t) of kera, from which less than a ton of tamahagane can be produced. A single kera can typically be worth hundreds of thousands of dollars, making it many times more expensive than modern steels.
Tamahagane
The swordsmiths will carefully break the kera apart, and separate the various carbon steels. The lowest carbon steel is called hocho-tetsu, which is used for the shingane (translated as "core-steel") of the blade. The high carbon tamahagane and higher carbon steel, called nabe-gane, will then be forged in alternating layers, using very intricate methods to form the kawagane (or, "skin steel"). The most useful process is the folding, where the metals are forge welded, folded, and welded again, as many as 16 times. The folding removes impurities and helps even out the carbon content, while the alternating layers combine hardness with ductility to greatly enhance the toughness. Currently, tamahagane is only made three or four times a year by Nittoho and Hitachi Metals during winter in a wood building and is only sold to the master swordsmiths to use once it is made.
Construction
The forging of a Japanese blade typically took many days or weeks, and was considered a sacred art, traditionally accompanied by a large panoply of Shinto religious rituals. As with many complex endeavors, rather than a single craftsman, several artists were involved. There was a smith to forge the rough shape, often a second smith (apprentice) to fold the metal, a specialist polisher, and even a specialist for the edge itself. Often, there were sheath, hilt, and tsuba specialists as well.
Forging
The steel bloom, or kera, that is produced in the tatara contains steel that varies greatly in carbon content, ranging from wrought iron to pig iron. Three types of steel are chosen for the blade; a very low carbon steel called hocho-tetsu is used for the core of the blade, called the shingane. The high carbon steel, called tamahagane, and the remelted pig iron, called nabe-gane, are combined to form the outer skin of the blade, called kawagane. Only about 1/3 of the kera produces steel that is suitable for sword production.
The best known part of the manufacturing process is the folding of the steel, where the swords are made by repeatedly heating, hammering and folding the metal. The process of folding metal to improve strength and remove impurities is frequently attributed to specific Japanese smiths in legend.
In traditional Japanese sword making, the low carbon hocho-tetsu is folded several times by itself, to purify it. This produces the soft metal, called shingane, to be used for the core of the blade. The high carbon tamahagane and the higher carbon nabe-gane are then forged in alternating layers. The nabe-gane is heated, quenched in water, and then broken into small pieces to help free it from slag. The tamahagane is then forged into a single plate, and the pieces of nabe-gane are piled on top, and the whole thing is forge welded into a single block, which is called the age-kitae process. The block is then elongated, cut, folded, and forge welded again. The steel can be folded transversely, (from front to back), or longitudinally, (from side to side). Often both folding directions are used to produce the desired grain pattern. This process, called the shita-kitae, is repeated from 8 to as many as 16 times. After 20 foldings, (220, or about a million individual layers), there is too much diffusion in the carbon content, the steel becomes almost homogeneous in this respect, and the act of folding no longer gives any benefit to the steel. Depending on the amount of carbon introduced, this process forms either the very hard steel for the edge, called hagane, or the slightly less hardenable spring steel, called kawagane, which is often used for the sides and the back.
During the last few foldings, the steel may be forged into several thin plates, stacked, and forge welded into a brick. The grain of the steel is carefully positioned between adjacent layers, with the exact configuration dependent on the part of the blade for which the steel will be used.
Between each heating and folding, the steel is coated in a mixture of clay, water and straw-ash to protect it from oxidation and carburization. This clay provides a highly reducing environment. At around 1,650 °F (900 °C), the heat and water from the clay promote the formation of a wustite layer, which is a type of iron oxide formed in the absence of oxygen. In this reducing environment, the silicon in the clay reacts with wustite to form fayalite and, at around 2,190 °F (1,200 °C), the fayalite will become a liquid. This liquid acts as a flux, attracting impurities, and pulls out the impurities as it is squeezed from between the layers. This leaves a very pure surface which, in turn, helps facilitate the forge-welding process. Due to the loss of impurities, slag, and iron in the form of sparks during the hammering, by the end of forging the steel may be reduced to as little as 1/10 of its initial weight. This practice became popular due to the use of highly impure metals, stemming from the low temperature yielded in the smelting at that time and place.
The folding did several things:
-It provided alternating layers of differing hardenability. During quenching, the high carbon layers achieve greater hardness than the medium carbon layers. The hardness of the high carbon steels combine with the ductility of the low carbon steels to form the property of toughness.
-It eliminated any voids in the metal.
-It homogenized the metal, spreading the elements (such as carbon) evenly throughout - increasing the effective strength by decreasing the number of potential weak points.
-It burned off many impurities, helping to overcome the poor quality of the raw Japanese steel.
-It created up to 65000 layers, by continuously decarburizing the surface and bringing it into the blade's interior, which gives the swords their grain.
Generally, swords were created with the grain of the blade (called hada) running down the blade like the grain on a plank of wood. Straight grains were called masame-hada, wood-like grain itame, wood-burl grain mokume, and concentric wavy grain (an uncommon feature seen almost exclusively in the Gassan school) ayasugi-hada. The difference between the first three grains is that of cutting a tree along the grain, at an angle, and perpendicular to its direction of growth (mokume-gane) respectively, the angle causing the "stretched" pattern. The blades that were considered the most robust, reliable, and of highest quality were those made in the Mino tradition, especially those of Magoroku Kanemoto. Bizen tradition, which specialized in mokume, and some schools of Yamato tradition were also considered strong warrior's weapons.
There is more here:
http://en.wikipedia.org/wiki/Japanese_swordsmithing
