Wind Rises in North America 1625

Chapter 86 Steel
"…When working iron into tools, we use wrought iron. First, we cast the iron into an anvil, the place where the hammer will be hammered. The saying that pliers are the ancestors of all tools is not an absurd statement. All wrought iron coming out of the furnace is called raw iron. During forging, three-tenths of it is lost as iron rust and iron chips."

"...When iron is bonded together, it is coated with yellow mud on the joints. Then, it is put into fire and hammered until the mud becomes a paste and removed. The spirit of the iron is used as a medium for bonding. After bonding, it cannot be broken even by a red-hot axe. When wrought iron or steel has been hammered in the furnace, but the water and fire have not yet reached the right state, its quality is not yet strong. When it is quenched in clear water while it is still out of the fire, it is called strong steel or strong iron. This means that when it is not yet strong, it is steel or iron, and its weakness still exists."

On December 12, a simple wooden shed was built next to the blacksmith shop in Shixing Fort.

Inside, a small experimental blast furnace was erected. The charcoal at the bottom of the furnace was burning brightly, quickly turning the iron material in the blast furnace into molten iron.

Ignoring the scorching temperature, several time travelers gathered around the blast furnace, all sweating profusely, their eyes fixed on the molten iron gradually solidifying into an anvil, and then instructing several craftsmen to start forging while the residual heat was still there.

On a wooden table far away from the small blast furnace, there was a book called "Raw and Cooked Iron Smelting Furnace" which was bought from the Ming Dynasty. The page had been turned to the fourth volume "Hammering and Forging".

This part records and describes the steelmaking process called "pouring steel method" and the corresponding refining steps.

Of course, the instructions in the book are only general and vague. Even if you follow the process described, you may not be able to produce qualified steel.

Therefore, this steelmaking experiment was mainly carried out by two blacksmiths from Foshan, with the information from "Raw and Cooked Ironmaking Furnace" serving as auxiliary explanation.

Blacksmiths first beat wrought iron into thin sheets, about an inch and a half long and about the width of a finger. Then they placed pig iron on the wrought iron sheets, covered them with mud, and put them into a blast furnace to heat them with blast air.

Under the action of high temperature, the pig iron melts first and penetrates into the wrought iron, and the two are fused.

Finally, it is taken out, hammered repeatedly, melted, and hammered again until the required steel quality is achieved.

The invention of cast steel seems to date back to the Han, Wei and Jin Dynasties, and matured in the Song and Ming Dynasties.

Moreover, cast steel uses pig iron and malleable iron as raw materials, and the casting operation is carried out above the melting point of pig iron, so the productivity is relatively high and the separation of slag and iron is better.

People can control the product composition by controlling the raw material ratio and air blowing operations, so the product quality is also better.

Before the invention of the crucible liquid steelmaking method in Europe (1740), all steelmaking processes in the world basically belonged to solid smelting and semi-liquid smelting, and it was difficult to separate slag and iron.

For example, cast steel has easier composition control and better separation of slag and iron. At that time, it was definitely a "high-tech" steelmaking technology.

However, the blacksmith Mu Shunan told the time travelers that a more advanced steelmaking technology, Sugang, had emerged in the Wuhu area.

This is a further technical improvement based on the previous steel pouring technology. Many people also call this technology pig iron pouring.

That is, pig iron and wrought iron are cast together, and when the pig iron begins to become fluid, the molten iron is poured into the wrought iron to produce Su steel.

Inspired by this technology, Ming Dynasty blacksmiths developed a friction-penetration technique for rapid surface hardening (heating the low-carbon steel that needs to be locally hardened, then quickly rubbing the heated area with a piece of pig iron, and then immersing it in water or oil for a while and then taking it out to cool, and then a medium-carbon steel with an extremely uneven hardening surface can be obtained).

It is worth mentioning that the Sugang method is unique in the world's metallurgical technology, and only the Ming Dynasty has this unique steel processing technology.

Although Sugang's production tools were still simple, the materials used were simple, and the energy consumption was extremely high, compared to the standards of later metallurgical technology, the production process was in full compliance with modern metallurgical principles.

What is even more rare is that this is a method that can separate slag and iron without a crucible, simply by oxidizing the iron.

Before more advanced metallurgical tools became popular, Sugang technology was still a method for producing qualified tool steel.

Even in the late 19th century, the quality of steel billets produced in Europe using the crucible method did not completely surpass the Su steel of the Ming Dynasty.

This technology was still in use in the 20s and 50s.

It can be said that before the more sophisticated industrial metallurgical technology, Sugang had the most advanced steelmaking technology.

none of them!

However, the Sugang technology had only spread to areas around Wuhu, reaching as far as Hunan and Xiangtan, and had yet to be widely adopted in Guangdong and the north. Mu Shunan had only heard of it briefly and did not fully understand the Sugang refining process.

However, for those who have traveled through time, refining steel using the steel pouring method can meet current needs.

At that time, there were few craftsmen and a small population, and the large-scale supply of raw materials (ores) could not be guaranteed at all.

Compared with the steelmaking technology in Europe at the same time, the pouring steel method not only speeds up the refining of finished products, but also ensures a higher steel output rate, which is enough.

"It seems... it didn't work!" Zhang Ruosong squatted on the ground, carefully looking at the steel billets that had been repeatedly melted and forged several times. When doing the brittleness test, they broke into two pieces. He shook his head slightly, a look of disappointment on his face.

"It didn't work again!" Mu Shunan also sighed in frustration.

He had already fired seven furnaces and consumed four or five hundred kilograms of iron. If he couldn't produce qualified steel, even if these "committee gentlemen" didn't blame him, he would still feel ashamed.

At the beginning, I was recruited here by these people at a high price to help them smelt iron and make various iron molds and tools.

Half a month ago, the "committee boss" named Zhang came to him with a book and asked if he knew how to make steel.

Mu Shunan immediately denied it, saying that he only knew some iron-making techniques and methods, and could not guarantee that he could produce iron in a short period of time. It would take some time for him to explore and experiment.

Iron smelting is still somewhat possible, but it may take some effort when you don't know the grade of the iron ore provided locally, the amount of impurities, and many other influencing factors such as the water absorption rate, strength, and melting characteristics of the ore.

These related factors need to be tested step by step, and it may be necessary to burn many furnaces of ore and still not produce qualified iron materials.

As for steelmaking, he only heard a few words from the master craftsmen at the Foshan Iron Works and had a general understanding of it.

But he really couldn't guarantee that he could produce real steel.

Commissioner Zhang did not make any harsh demands on him. Instead, he asked him to first take people to build an iron-smelting blast furnace and prepare for the iron-smelting trial.

The iron-smelting blast furnace was already very mature as early as the pre-Song Dynasty. The entire shape of the blast furnace is like a large waist drum in the folk, thin at both ends and thick in the middle.

This shape can make the gas distribution more uniform, ensure full contact between the charge and the gas, save fuel relatively and extend the life of the furnace wall.

The autumn harvest was over and there was plenty of manpower. In less than a day, they built an experimental small iron-smelting furnace that could smelt about fifty to sixty kilograms of ore each time.

After six or seven days of smelting, a furnace of more than 20 kilograms of molten iron finally flowed out from the bottom of the furnace, making everyone excited.

Mu Shunan happily told Commissioner Zhang that the iron content of these ores was quite high, much higher than the Dong'an (now Yunfu) iron ore used by the Foshan Iron Works, and the iron content might be as high as 60% to 70%.

If he built a blast furnace with a larger capacity and had sufficient ore, he could guarantee that he could produce tens of thousands of pounds (one pound in the Ming Dynasty weighed about 596.8 grams, one pound equaled sixteen taels, and one tael was about 37.3 grams) of pig iron and wrought iron a year to meet the needs of Shixing Fort.

However, Commissioner Zhang did not seem to be very satisfied with this. In addition to wanting to increase the iron production to 100,000 to 105,000 jin in the next two to three years, he also wanted to produce steel.

Mu Shunan's face suddenly turned bitter when he heard this.

These "gentlemen" don't get their money for free!
So, these days, Mu Shunan and other craftsmen began to test steel making based on the little steel making experience they had heard and the book "Raw and Cooked Iron Making Furnace" brought by Commissioner Zhang.

They said that steel may not be used on a large scale now, but there must be corresponding "technical reserves".

At present, the technology and process steps of steelmaking have been gradually determined through a slow and exploratory test process. When all production conditions are mature and the scope of steel application is expanded, we can immediately build a blast furnace and start large-scale smelting.

This is called preparing for a rainy day and planning ahead.

Well, since the "managers" of Shixing Fort don't mind the trouble and are willing to waste precious iron, let's just follow them.
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(End of this chapter)