In the traditional steelmaking method, there is a "stir-fried steel method", which first uses iron sand to smelt pig iron, and then melts the pig iron, stirring it continuously during the process to decarbonize the pig iron. Depending on the degree of decarbonization, it can become iron or steel. Grass steel is obtained by using Longquan iron sand in this way. Because "stir-fried" and "grass" are homophones, and the steel produced is rough and sloppy in appearance, it is called "grass steel" in Longquan dialect. It is the best blade material for swords. Since the Qing Dynasty, Longquan can only smelt rough iron, and "grass steel" has been lost for nearly a hundred years. Recently, it has been committed to replicating and restoring the ancient traditional sword forging technology and has restored "grass steel".
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Grass steel forging: Grass steel is pig iron with a high carbon content, not steel. Only carbon-iron alloys with a carbon content of less than 2% can be considered steel. Grass steel is made of gravel-like iron oxide selected from the river in the mining area. It is in the water all year round, so it contains low sulfur and phosphorus. Because these two harmful elements are soluble in water, they are easily hydrolyzed, leaving behind low-harmful ore sand. The advantage of using these iron ore sands and charcoal or bamboo charcoal to refine them is that they will not add additional harmful elements of sulfur and phosphorus. Because this type of pig iron is not produced in a blast furnace, the temperature cannot reach 1500° and the molten iron cannot be completely liquefied, so the carbon content is uneven during the refining process. Many bubbles that cannot be eliminated during the smelting process make the pig iron sponge-like. This type of raw material is called "grass steel" by knife makers.
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Iron sand has a relatively high viscosity. Therefore, the swords made from it have high toughness and hardness. The patterns forged from grass steel swords are also different from other patterned steels. And because the material is scarce, grass steel swords are even rarer. They are not only strong in performance, but also have collection value. The swords made by Longquan are famous because of such rare materials.
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The knives made by further forging (reducing carbon) this type of pig iron are called grass steel forgings, which are the same type as the tamagoyaki in this book.
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Based on the common sense of iron smelting, the decarburization of pig iron must reach a temperature of 1400°, otherwise the iron cannot accommodate more oxygen atoms to react with it, and the iron element will not be evenly penetrated by the fuel "carbon", and a large number of bubbles and holes will be generated inside to form a sponge. Therefore, the bottleneck restricting the development of the steel industry since ancient times is the furnace temperature. China's steel-making method is likely to be fabricated. There is no historical basis and physical objects. The only reference is the record in "Heavenly Creations". If you study it in depth, you will find that the "lump steel" and "stir-fried steel" at that time were made of soft iron (with a very low carbon reduction) that had been forged N times and then mixed with pig iron for high-temperature forging to reduce the workload. This process adopts high-temperature forging, not the real liquid iron decarburization technology. The molten iron at about 1200° is very viscous, just like the state of "porridge" or "paste". The iron in this state cannot be simply decarburized, and the real liquefied molten iron must reach more than 1500°.
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Forging at a temperature above 1000°. The advantage of high temperature forging is that the metal is softer and easier to shape. The reason why "patterned steel" rarely appeared in ancient Europe is that they always adopted high temperature forging, not low temperature forging. It is difficult for the metal to leave forging marks. Low temperature forging is folding forging within 1000°, which is very easy to leave "welding" marks. The characteristic is that the labor intensity will be greatly increased, but it can leave marks. Another reason is that ancient Europe lacked "borax", a natural welding agent, while Asia can see it everywhere.
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Some things are not as magical as they seem on the surface, such as the jade steel of the book, which only represents a tradition and culture.
