Tao Qiqi carefully polished the graphite crucible mixed with clay smooth, and asked Du Zhongxiao on the side curiously: "Official, what is this pot used for?" Graphite is originally used to make ink, and it is the right way to make a pen, so it is difficult to burn, what is the use of using it to make a pot? ”

Du Zhongxiao said: "It is precisely because it is difficult to burn that it is used to make pots." In the past, it was difficult to make good steel, mostly because it could not be burned. Only by using this pot, boiling the pot into molten iron and stirring evenly, can the steel be produced. ”

Tao Qiqi was so confused that he didn't understand it, so he simply didn't ask, just polished the small pot with peace of mind.

According to Du Zhongxiao's instructions, a few craftsmen over there built a stove on the slope, just enough to put this crucible on it. The stove is conducive to heat preservation underground, and most of the exposed ground is conducive to operation, and it is also conducive to people observing from the furnace mouth above during the refining process.

Seeing that it was approaching evening, Du Zhongxiao said: "Let's eat first, and then fight at night." This matter is urgent, and it must be done day and night to get the required steel out. If the knife is made well, it can be used to make steel and make some precious iron tools in the future. ”

Dong Zhushu and Chai Xin thought that the knife made of steelmaking in this way was cheap, but it was actually not cheap. Du Zhongxiao can do this, because he is the magistrate of the county, and he can recruit manpower at a very low cost. If it is really completely commercialized, the cost is high, and the market is lacking, how can the price of the tool steel made in this way be low? It's just that I'm in a hurry to use the money now, so I have to use this method to save the emergency first.

After eating, a few large torches were lit and the surroundings of the construction site were illuminated as if it were daytime. The stove had been set up, and Tao XVII put the crucible on it, and took the craftsman to heat the stove there. Because there was no coke, Du Zhongxiao was worried that the calorific value was not enough and could not reach the required temperature, so he opened a few more vents on the stove and used three bellows to supply air to the inside. In the previous life, because the furnace could not reach the specified temperature, a pile of scrap iron was finally smelted because the furnace could not reach the specified temperature. The key to crucible steelmaking is to melt the steel inside into a liquid before it can be fully stirred to form homogeneous steel.

Chai Xin looked strange on the side, and said to Du Zhongxiao: "Official, the little one has lived for decades, and it is the first time to see iron smelting like this." I used to hear that frying steel is also to fry iron in a pot and fry it, is this the method? ”

Du Zhongxiao thought for a while before saying: "Stir-frying steel is stir-fried after all, just like stir-frying, just add some seasonings." Now this method, compared with fried steel, should be regarded as a soup, the heat is enough, and the coming out is of course not the same thing. ”

Frying steel is to use the high carbon content in pig iron to increase the carbon content of fried steel. Due to the simultaneous decarburization, the carbon content of the steel is low, and it still needs to be carburized before it can be quenched to achieve the required hardness. This kind of complex change, Du Zhongxiao can't explain it clearly, how can he explain it to Chai Xin? The change of carbon content in iron directly affects the performance of steel, and there is a lack of detection means in this era, but also a lack of control means, how can it be said clearly. I can only make a rough idea, and I can only slowly accumulate experience and conduct research.

Over there, Tao Qiqi was so hot that he was sweating profusely, and he couldn't help but come over and say to Du Zhongxiao: "Official, when will this stove be baked?" ”

"When you see that little pot of graphite red, you'll be ready to go. There is no urgency in this matter, so be patient. ”

Tao XVII agreed, and ran over to look at the blazing stove.

It is difficult to control the carbon content of the steel in this way, and Du Zhongxiao has no way to do this. I can only wait until I have done it for a long time, and I don't know if anyone can practice makes perfect and find a way. However, as long as it is a high-carbon steel, the hardness after quenching is sufficient.

When the crucible burned red, Tao Seventeen ran over excitedly and said, "Official, it's done!" ”

Du Zhongxiao got up, went to the furnace and looked at it, the crucible made of graphite and clay was already burned red, so he ordered the craftsmen on the side to put the prepared pig iron into it and cover the furnace lid. Pig iron is released first, and the air inside the furnace can be used to decarburize.

Instructed Tao Seventeen to find the small hole in the lid every once in a while, and wait for the pig iron inside to melt and report.

The night was breezy and silent, and I don't know how much time had passed, Tao Seventeen shouted over there: "Official, it's molten iron inside!" ”

Du Zhongxiao read it and ordered to pour the prepared lime and soda ash into it. At this time, most of the coal was used to make iron in the north, and there were too many impurities in it, so it was necessary to add these things to remove the impurities. After stirring evenly, he ordered to stop, and when the residue sank to the bottom of the crucible, Du Zhongxiao ordered to put the prepared wrought iron into it. The craftsmen who were watching were instructed to start stirring when the wrought iron had melted.

Chai Xin looked at it with great surprise on the side, and saw that Du Zhongxiao was doing these things calmly, as if he was used to doing it, and said "huh" from time to time.

Of course, Du Zhongxiao didn't do it, but he just did it step by step according to the principles learned in his previous life. As for what the final steel looks like, to be honest, he doesn't have a bottom in his heart. It's just that I am the biggest official here, so I don't need to pay attention to what others think, just do it.

The wrought iron over there was melted, and the workers kept stirring it with iron rods.

At this time, the moon is in the middle of the sky, and the moonlight is sprinkled like water, and the surrounding scenery is a little hazy. Du Zhongxiao looked at the night, feeling the scorching fire over there, and his spirit was a little dazed for a while, and he felt a little unsure of what day it was. This kind of hot scene has not been experienced for many years, and I am a little nostalgic and fascinated for a while. Sitting in the yamen every day, dealing with all kinds of official documents, Du Zhongxiao was also depressed. He did not have the habit of the literati of this era, and he had not yet learned to write poems and lyrics proficiently, so he relaxed on this occasion.

Tao Seventeen shouted over there: "Official, the molten iron in it has been stirred evenly, and there has been no change in the past half a day!" ”

Du Zhongxiao went to the fireside and looked through the small hole in the lid. In fact, I couldn't see anything, but I saw that it was even inside, and there were some signs of boiling, so I said: "Stop, seal this small hole, cool it for half an hour, and then take out the crucible, pour out the molten iron and pour it into the mold." ”

At this time, the furnace is in an oxygen-deficient environment, and it is necessary to wait for the molten iron to stabilize before taking it out.

Tao Seventeen was so anxious that he kept walking around the stove back and forth, Chai Xin was curious, stretched his neck to the stove to look, and said to Tao Seventeen: "Seventeen, you said that this can really come out of good steel and make a treasure knife?" ”

Tao Qiqi said impatiently: "If the official says so, it must be okay." An official was born as a scholar, how many books did he read? I must have learned this method from some secret book, how could it be wrong! Chai Jie, you are a person close to an official, how can you ask such a thing? ”

Chai Xin shook his head, turned to the side, and looked at the stove, obviously not believing it. Today, the two treasure knives on the dock compared to cutting copper coins, which gave him a great shock, thinking that it was a rare treasure in the world, how could it be made so easily?

Listening to Tao Seventeen's words, Du Zhongxiao wanted to laugh a little. It's good that I was born as a jinshi and read a lot of books, but where can I have this kind of knowledge in those books that can be read for the jinshi exam? The imperial court selects jinshi to govern the country, not to be craftsmen.

Thinking of this, Du Zhongxiao sighed slightly. In fact, it is good to run a school to recruit students to teach this knowledge, but now I am a soft-spoken person and I am beyond my ability to do these things. Now there is no formal school in Yongcheng County, and no one teaches or learns serious classics, so how can this kind of school be established? Only when the economy is prosperous for two years can I make this start.