In fact, Ma Chao didn't realize what kind of impact his fluttering words had on the entire Han Dynasty.

'Pig iron and wrought iron are practiced together, and a few nights become steel......

This passage is actually from the writings of Qi Wuhuaiwen of Wei and Qi in the Northern Dynasties more than 600 years AD, that is, more than 400 years after the end of the Han Dynasty.

Qi Wu Huaiwen, surnamed Qi Wu, named Huaiwen, was a famous metallurgist during the Northern and Southern Dynasties of China. He lived in the Eastern Wei Dynasty and Northern Qi of the Northern Dynasty in the 6th century AD, and was good at Taoism, and once made the history of the Xinzhou Assassin of the Northern Qi Dynasty. He used this method to create an extremely sharp "Iron Knife".

The iron knife is actually a steel knife. Su Iron is named after its manufacturing method, and the manufacturing method of Su Iron is actually the famous steel filling method.

In the history of Chinese metallurgy, after the development of 'block smelting'--100 steelmaking'--'frying steel', the steel-filling method appeared.

Before the Spring and Autumn Period, the ancient Chinese smelting technology was in a relatively primitive stage, and the smelting method used at that time was called the 'block refining method'. At that time, charcoal was used as fuel for ironmaking, and the heat was small, and the furnace body was small and the blower equipment was poor, so the furnace temperature was relatively low and could not reach the smelting temperature of iron, so the iron smelted was a sponge-like solid block, which was called "block ironmaking".

Block iron smelting is more time-consuming, the texture is relatively soft, contains many impurities, and it is forged into wrought iron that can be used. In the process of forging block iron and wrought iron, people need to continuously and repeatedly heat, and the iron absorbs the carbon in the charcoal, improves the carbon content, and reduces the inclusions to become steel.

This steel has a tight structure and uniform carbon content, making it suitable for making weapons and knives. Later, it was further developed to the "100 steel" technology.

When people make utensils, they consciously increase the number of folding and forging, and a piece of steel often needs to be burned and burned, and repeated many times, or even hundreds of times, so it is called 100 steel.

The carbon content of 100 steel is more, the structure is more fine, and the composition is more uniform, so the quality of steel is improved, and it is mainly used to make knives and swords.

Therefore, in ancient times, what kind of earth-shattering artifacts were born, such as the cadre, Mo Xie, and Juque Shenma, which were forged seventy-seven forty-nine or ninety-eighty-one days or the like, don't be fooled by this: that's because the level of that era was too backward, and people spent so long knocking iron blocks to play because they couldn't make good steel.

Then, around the middle and late Western Han Dynasty, a new steelmaking technology 'fried steel' appeared in China, which was developed on the basis of pig iron smelting and casting technology. The basic method is to heat the pig iron into a semi-liquid and liquid form, and then add iron ore powder, while constantly stirring, using iron ore powder and oxygen in the air to remove part of the carbon in the pig iron, so that the carbon content in the pig iron is reduced, slag is removed, and the steel is directly obtained, which is the steel frying technology.

The invention of this technology was a major breakthrough in steelmaking technology, enabling the smelting industry to provide society with large quantities of cheap, high-quality wrought iron or steel to meet the needs of production and warfare. The emergence of fried steel has also promoted the development of 100 steel-making technology, and people use fried steel as raw material, which has been repeatedly heated, folded and forged into steel parts of good quality. However, there are still certain defects in the technology of frying steel and 100 steelmaking, such as the process of frying steel is complex and not easy to master; 100 steelmaking is labor-intensive and time-consuming.

At the end of the Han Dynasty, where Ma Chao lived, the level of iron smelting also developed to this stage. In other words, at this time, it is also difficult to get a good steel knife. Because the quality of steel is still unstable, and secondly, it is time-consuming and laborious to forge steel. Finally, there is the single-liquid quenching method, which makes the steel knife either hard and easy to break, or unfavorable tough.

A fact can illustrate this: Boss Cao is a knife lover, and the seven-star treasure knife that deceived Wang Yun at the beginning was given to Dong Zhuo in order to save his life. Later, when he became the king of Wei, he suddenly remembered this, so he ordered Yousi to make five treasure knives, but he never thought that the treasure knife was made, but it took three years!

It was not until the advent of the steel filling method that the problem of quality and yield was solved in one fell swoop. Moreover, compared with Ma Chao's steel frying method in this era, the steel filling method obviously has four major advantages.

One is to shorten the smelting time and increase productivity; The second is that pig iron and wrought iron can be turned into steel, which improves the output of steel; The third is to purify the metal structure by filling steel and improve the quality of the metal; Fourth, the steel filling method is easy to operate and easy to master. If you want to obtain steel with different carbon contents, you only need to mix pig iron and wrought iron in a certain proportion and smelt them.

As for the sentence 'using soft iron as the spine, bathing with five animal urine, quenching with five animal fat, ......', it actually refers to the two-liquid quenching method.

Double-liquid quenching method, that is, when the temperature of the workpiece is relatively high, the quenching medium with fast cooling speed is selected to ensure the hardness of the workpiece; When the temperature is relatively low, the quenching medium with a relatively small cooling rate is selected to prevent the workpiece from cracking and deformation, so that it has a certain toughness.

The two-liquid quenching method is a relatively complex quenching process, and under the condition that there is no temperature measurement and temperature control equipment at this time in the late Han Dynasty, it can only completely rely on the operation and experience of craftsmen.

It can be said that the emergence of the steel filling method and the double-liquid quenching method also made the steel knife of that era a real treasure knife.

And Ma Chao has eyes and doesn't know Mount Tai, and he is completely a loser who abandoned watermelons and picked up sesame seeds. At this time, after seeing Pu Yuan waking up, he didn't immediately let Pu Yuan carry out the test of the steel filling method and the double-liquid quenching method. Instead, he brought a wooden board and said mysteriously: "Master Pu, this kind of thing is called a horseshoe." Let you create ten pairs in two days, can you do it? ”

The horseshoe does not require a high level of craftsmanship at all, and the technology and personnel of the iron shop at this time can be completely competent. And after Pu Yuan asked about the specific size and specifications, he readily agreed.

"In a few days, after I have tested the efficacy of this horseshoes, let Captain Huang send another 300 blacksmiths, and at that time, Eunuch Pu will be carefully guided, and 20,000 pieces must be made!" Thinking that the ugly brother's hard work to buy the plan was almost underway, Ma Chao estimated that in the next few days, the iron shop should be expanded.

"The villain will not be dishonored!" Pu Yuan laughed even more happily when he heard that the number of people under his command was going to increase.

"Don't call yourself a 'villain' anymore, my blacksmith eunuch, you should call yourself 'lowly'!" Ma Chao said with a smile. He even patted Pu Yuan's shoulder to show encouragement.

And Pu Yuan was also flattered, and replied excitedly: "The villain knows ......"

Ma Chao's face was black: It seems that if you want to change the humble thoughts of these people, you still need to work hard.

However, not long after, when Pu Yuan had successfully studied the steel filling method and the double-liquid quenching method, and was promoted to Ma Chao's subordinate as no less than those generals, Ma Chao slapped the table and shouted: "Good Pu Yuan, why did you report such a wonderful method at this time?" Was that bastard the horseshoe that let you nail some Rausch? ”