1. Japanese knives are made of steel called Wakou or Tamahagane. Jade steel is made by traditional Japanese indigenous method. This is a low-temperature steelmaking method, and the furnace temperature does not exceed 1000℃. This method seems primitive, but compared with modern high-temperature steelmaking, it can produce good steel with pure quality. But steel refined at high temperature is soft and easy to make, while steel refined at low temperature is hard and difficult to make. It can be said that making Japanese Dao is a labor-intensive fortification, and it is the product of the quality of mountain city in exchange for blood and sweat. According to different regions and schools, the composition of steel used will be different. Generally speaking, the composition of Yugang is shown in the table.
Composition Table of Jade Steel (World War II: iron 98. 12%-95.22% carbon 3.00%-0. 10% copper 1.54% manganese 0.1%tungsten 0.05)
2. The quenching process, the so-called heat treatment, is called Mizuho in Japan. From the perspective of modern materials science, this step can be regarded as a method for tool makers to control the carbon content of steel. Knife makers hammer the heated steel into a flat plate with a thickness of about 5 mm, which seems to be a simple process, but it is not. In order to control the carbon content of steel, the heating times are strictly limited. Moreover, the hardness of steel will change when it is gradually cooled. Only experienced knife workers can accurately grasp the change of hammering strength and forge jade steel into thin slices with uniform thickness under limited heating times.
3. Exercise: The knife man will beat and forge the red-hot steel block, and then fold and beat the steel block after hammering. Repeat this process until 10, and there will be 1024 layer steel. Through this step, impurities such as sulfur and excess carbon in steel can be removed, and the elasticity and toughness of steel can be increased. It's like kneading dough. The more layers are knocked, the more uniform the carbon and various components in the steel are, and the more detailed the crystallization of iron is. Finally, the forged steel will have a uniform quality, reaching thousands of layers, which is very strong.
4. The shape of the knife is extended into a strip of Su Yan, which is called Su Yan (すのべ, sunobe), and the prototype of the knife basically appears at this stage. After this step is completed, the cutter union will cut off the front part to make the tip of the knife.
I hope it will help the landlord.