The Japanese Samurai Sword Manufacturing By 谌泓宇 Chen HongYu

Steel making—— Steel and Tahamagane The component of the Tahamagane Iron % % Carbon % % Copper % Manganese % Tungsten % Molybdenum % Titanium % Silicon not quantitative

Mizuheshi Heat the Tahamagane and strike it with hammer to make it into the chips with 5cm thickness. The times of heating is limited strictly in order to control the carbon content in the Tahamagane. And that makes it very difficult to handle the power and the timing. After the steel chips are taking shape, they will be cooling by water. And the parts in which there is enough carbon will drop from the chips naturally. And those dropping parts will be used to make the Samurai Sword.

Kowari & Burning Platform Making Kowari: Smash those steels into tiny shape(About 2~3cm long). Some of those steels which cannot be smashed have lower carbon content and are generally used as the making material of the sword center. This step is aimed at delivering the heat averagely in the following steps. Burning Platform: it will become a part of the final sword, so it should be making by Tahamagane of high quality. Burning Platform

Tsumikasane Weld the tiny steel chips onto the Burning platform one by one and layer upon layer. The heating stickiness of the steel depends on the carbon content, so the first step Mizuheshi is very important. Several different kinds of welding ways: 1.Parallel 2.Orthorhombic 3.Cross The needed steel: 2~3kilogram

Tsumiwakashi Put the product of the last step back into the heating furnace to make sure these steels can be welded together completely. In order to avoid the carbon element within the steels being oxidized, before entering the furnace, the steel block will be wrapped up by a special kind of paper which is stained with mud and ashes of straw. The temperature and the duration of the heating process have to be controlled carefully.

Repeating Tempering Strike the steel block coming from the furnace until it is flat. Then fold the steel half and half, and put it into the furnace again. Repeat this process for several times. After 10 times, steels with 2^10=1024 layers will be produced.

Combination & Initial Shaping Shintetsu Outside part Kawatetsu Inside part Kawatetsu is more stiff. The component material is the steel of high carbon content which has been tempering for 10 to 15 times. Shintetsu has the property of toughness. The component material is the steel of low carbon content which has been tempering for 5 or 6 times. After combination, the steel will be made into the basic shape of a sword.

Quenching & Tempering Quenching: the sword with basic shape will be put into the heating furnace with high temperature of 750~760 centigrade, and then cooling rapidly in the water. Before quenching, the surface of the sword should be daubed a layer of special clay. The layer on the blade is thin and become more thick when approaches the other side.

Tempering: put the sword back into the furnace again after quenching and take it out rapidly after a certain time of heating. The sword will be cooling slowly in the air.  In the quenching process, due to the different thickness of the clay, the cooling speed of the steel is also different. The cooling speed of the blade is the highest, and more austenite will transform into martensite which is harder. And because the changing from austenite to martensite will cause the volume increasing, the final shape of the sword will follow a beautiful curve.

Polishing & Lettering

Finished