How long it can hold the edge is also dependent on the material used. The sharpness of a sword, and ability to keep that edge, is based on the angle of the edge and the width of the body of the sword. After the sword was polished, the fine tip could be sharpened. This process is long and tedious, but a good polisher was of great value to the swordsmith and was often paid well. They would polish and sharpen the sword until the desired finish was achieved. Some grinding rocks can range in the thousands of dollars today. Once the blade had been heat-treated, a sword would be ground with progressively finer abrasives, typically different types of rock. Polishers and finishers Two Japanese waterstones Then he would pass it on to a polisher and finisher. Once the sword was red hot the swordsmith took the newly formed sword and quenched it in water, hardening the blade. Once the sword took the shape the swordsmith wanted, the swordsmith would clay the spine of the sword, called tsuchioki, and heat it once more. ĭepending 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. After 20 foldings, 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. This process, called the shita-kitae, is repeated from 8 to as many as 16 times. Often both folding directions are used to produce the desired grain pattern. The steel can be folded transversely or longitudinally. The block is then placed back in the fire. Taken out of the fire and hammered into a thinner block, the block is scored in the center with an axe and folded over, making it thick again. In the process of forming, the block is heated to around 900 degrees Celsius. The swordsmith takes the tamahagane nuggets and forges them into a block. The tamahagane is then cooled and the smelter selects the best pieces to send to the swordsmith. The process starts in the combining of the iron and carbon, by heating iron sand to 1200-1500 degrees Celsius in a traditional furnace, or tatara, for 72 hours. This allows the sword to have the strength and the ability to hold a sharp edge, as well as to cause the sword to tend to bend rather than flex under stress. Japanese smiths discovered, similarly to many others, that iron sand (with little to no sulfur and phosphorus) heated together with coal (carbon) made the steel they called tamahagane.
Bronze alloys with lower tin content are tougher, or more resistant to fracturing.
Some Chinese swords used high-tin bronze for the edges, since it is harder, and keeps a sharp edge longer, but is more brittle than the softer, lower-tin alloy used for the blade's core. Secondary operations involve removing material from the roughcasting, polishing, and the application of decorative elements. Finally, it should be balanced along its length so that it can be wielded effectively.īronze swords Apa type swords, 17th century BC.īronze items are typically cast, not forged.
#Different metals for katana blades crack#
At the same time, it must be strong enough and flexible enough that it can absorb massive shocks at just about any point along its length and not crack or break. The Roman gladius was an early example of swords forged from blooms of steel.Ī good sword has to be hard enough to hold an edge along a length which can range from 18 in (46 cm) to more than 36 in (91 cm). Bronze swords were stronger by varying the amount of tin in the alloy, a smith could make various parts of the sword harder or tougher to suit the demands of combat service. Early swords were made of copper, which bends easily. While there are many criteria for evaluating a sword, generally the four key criteria are hardness, strength, flexibility and balance. Swords have been made of different materials over the centuries, with a variety of tools and techniques. Sword making, historically, has been the work of specialized smiths or metalworkers called bladesmiths or swordsmiths. JSTOR ( September 2014) ( Learn how and when to remove this template message).Unsourced material may be challenged and removed. Please help improve this article by adding citations to reliable sources. This article needs additional citations for verification.
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