Chapter 21 Chapter Three Formation of Chinese Traditional Science and Technology

In the late Spring and Autumn period, steel products came out in our country. In 1976, a steel sword at that time was unearthed in Changsha, Hunan Province. It was a medium-carbon steel with a carbon content of 0.5% to 0.6%. It was forged repeatedly, indicating that there was a steelmaking process at that time.In the early steelmaking process, the sponge iron was directly heated in hot charcoal to carburize the surface, and then forged to form carburized steel.The emergence of steelmaking technology provides stronger and sharper tools and products, which is a major achievement of smelting technology.

However, the early steelmaking process can only produce small items, and it is time-consuming and labor-intensive, with low output and no guarantee of quality, so it is difficult to meet the society's demand for steel products.In the face of mass-produced pig iron, how to improve its quality has become a concern of smelters.Finally, in the middle and late Western Han Dynasty, a major technological breakthrough was made, and a new steelmaking process - "fried steel" was invented.The so-called "fried steel" (also known as "fried iron") is to heat the pig iron in a frying furnace to make it melt or basically melt, and keep stirring to increase the contact surface between oxygen and pig iron to oxidize the carbon in the pig iron. , and decarburized into steel or mature iron.This connects and combines the two major processes of pig iron smelting and steelmaking (or wrought iron) to form an organic smelting system that can be produced continuously and on a large scale, thereby greatly improving production efficiency and reducing costs. , so that steel products are easy to popularize.Therefore, its appearance has changed the appearance of the entire iron and steel production, and it is an epoch-making event in the history of metallurgy.

The invention of the method of frying steel promoted the development and maturity of steelmaking technology.From the Eastern Han Dynasty to the Southern and Northern Dynasties, the most sophisticated steel was called 100-refined refined steel or 100-refined steel.It uses fried steel as raw material, after dozens or even hundreds of times of repeated heating and folding and forging, it becomes a high-quality steel with dense structure and uniform composition.The sword made of 100-refined steel is extremely sharp and is regarded as a treasured sword and sword.During the Jian'an period of the Eastern Han Dynasty (196-220 A.D.), Cao Cao ordered craftsmen to make five precious swords, which took three years to complete.He kept two for himself, and one for each of his three sons.Cao Zhi specially wrote an "Ode to the Precious Sword" for this purpose, saying that "the land cuts the rhinoceros leather, and the water breaks the dragon boat", which is sharper than the famous swords Juque and Tai'a.

Another major achievement in steelmaking technology is the invention of steel pouring technology.It originated around the end of the Eastern Han Dynasty and was basically mature during the Southern and Northern Dynasties.The process is roughly as follows: melted pig iron and wrought iron are smelted together, the carbon in the pig iron will diffuse into the wrought iron, and tend to be evenly distributed, and some impurities can be removed to form steel.The smelting expert Qi [qiqi] Mu Huaiwen of the Northern Qi Dynasty used this method to make the "Su Iron Knife", which was sharp enough to "cut armor beyond thirty swords" ("Northern History·Qi Mu Huai Wen Biography").Before the invention of the crucible (ganguo Ganguo) steelmaking method, the pouring method was the most advanced steelmaking technology.

Pig iron smelting, together with these advanced steelmaking technologies, has been inherited by later generations.The reason why China has been able to occupy the leading position in the world's steel production for a long time in history is inseparable from the technical guarantee they provide.