Reading Selection, Lesson 18
The Samurai's Sword
To make a katana, a swordsmith used two types of steel. The core of the sword was made of soft, flexible, low-carbon steel (an alloy of iron with a little carbon). The jacket, or outer part of the sword, was made of hard steel that contained a greater proportion of carbon than did the core.The combination of these two kinds of steel gave the sword theflexibility to withstand a hard blow and a hard, razor sharp edge that would not be dulled during battle.
The swordsmith treated both steels with different techniques that improved the performance of the sword even further. He began by heating a lump of raw low-carbon steel—about the size of a brick—in a forge (a furnace that burns charcoal at very high temperatures).
The swordsmith then hammered the steel on an anvil until it was flat. Then he folded it in half crosswise and hammered it out again. He repeated this process many times to drive out any impurities from the metal.
Finally, he shaped it into a long, thin wedge. Next, the swordsmith began to work on the high-carbon steel. He followed the same process as the one he used for the low-carbon steel, but this time, he hammered and folded many more times. The final piece of metal had up to 30,000 folds or layers. The swordsmith made the jacket somewhat longer than the core.
Next, he joined together the two parts of the blade. The jacket was wrapped around the core, and the swordsmith heated and hammered the two pieces until they formed a solid bond. He had to be extremely careful; if an air bubble or piece of dirt remained between the two parts of the blade, the sword would be worthless in battle.
The blade was then tempered, a process that is used to control the properties of the steel. The blade was heated and then cooled by being plunged into water. The swordsmith coated the sword with clay to control the cooling process. Where the coat of clay was thick, the steel would cool more slowly, and this would make it flexible. The edge of the blade was given a thin coat of clay, which allowed it to cool very quickly, a process that made the edge even harder.
The swordsmith sharpened and polished the blade. The layers, or grain, were visible on the shiny surface. Finally, he tested the blade—on iron sheets, armor, and, sometimes, the bodies of executed criminals.
The Samurai swords were deadly but beautiful. The blades were decorated, and the handles were inlaid with pearls and other jewels.
Samurai swords were passed from generation to generation. Upon reaching manhood, a son received his father's sword, along with stories of the brave acts that had been accomplished with it.
What techniques did the swordsmith use to modify the properties of different parts of a katana blade? Investigate how these techniques are applied for different purposes today.