The next day, a few of them began to teach Ashin and a dozen teenagers to sail in the Yan'an River, and they used a patched hard sail.

On the raft, the hard sail fluttered in the wind, and the Lehi Dog told these people how to face the wind through demonstration and body language.

The traditional hard sail can also be adjusted against the wind, that is, the practice of constantly changing the direction of the bow of the boat, so that the boat can go zigzag against the wind.

Although not as efficient as a spinnaker, a stiff sail can still make better use of the wind when the wind is downwind.

Therefore, by the middle of the 16th century, Western ships began to use a mixture of crosssails and spinnakers, which could maximize the use of wind power and be more suitable for ocean voyages.

And the reason why Yan Zheng let them practice in the river first is not only to let these landlubbers have the concept of wind direction first, but also to let them explore the spinnaker.

As soon as he thought of the Heishuigou in the Taiwan Strait, Yan Zheng felt that they had to learn the spinnaker technique, otherwise they would need to take Penghu to reduce the risk every time they crossed.

The second is that the ship will be bigger in the future, and if the ship is not big, it is likely to cause the tragedy of "six deaths, one stay and three turns".

And after knowing the smuggling situation in Fujian at this time, Yan Zheng had the idea of communicating with Fujian, and he felt that as long as it was profitable, Fujian's maritime merchants might not come to Dongfu.

It is certainly not possible to go out on your own, you must walk on two feet, on the one hand, go out, and on the other hand, bring in.

Anyway, with graphite, Yan Zheng naturally has greater confidence to carry out more open foreign exchanges.

Although there is a limit to the output of the crucible steelmaking method, no one can deny that this thing has brought the spring of the machinery industry!

Historically, this method was invented in 1742 by the Englishman Hunzman. Even when Watt was able to improve the steam engine, it benefited from the large-scale use of this technology.

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The Meaux ironworks, with its iron-making furnaces and iron-frying furnaces, have increased to three, and the production of iron has recently increased considerably due to the large number of high-quality coolies invested in mining.

The number of full-time iron-striking clansmen has reached thirty-four, and ironwood needles can already be called journeymen!

He played the first iron pot in the tribe last month, although this iron pot is not big, but it is of great significance, because Yan Zheng can finally eat the dishes stir-fried in the iron pot!

It's just that in the face of Yan Zheng, his face didn't have the pride of the past at all, he stood respectfully, watching Yan Zheng tinkering with new things.

This time, Yan Zheng also took more than a dozen of his brightest students to start this steelmaking practice.

In order to make the best use of these graphites, he deliberately got his hands on it. The formula of graphite crucible is also required, sometimes as long as the origin of iron is different, then the steel may have different properties.

According to his own guess, after careful consideration, Yan Zheng directly applied to a formula of high-carbon steel, in which graphite accounted for 50%~55%, clay accounted for 30%~40%, and aggregate accounted for 5%~15%.

Once the recipe is chosen, it is time to start making a mold, which is directly made by the people of the woodworking factory. Yan Zheng took into account the thermal insulation conditions and the size of the existing pliers, and deliberately chose only a size that could smelt about ten kilograms of iron at a time.

Yan Zheng first added water, mixed graphite, clay and aggregate little by little, in order to ensure maximum uniformity, he let the two powerful clansmen constantly stir.

As he commanded, he said to the students who were observing, "Did you see that? Graphite, clay, aggregates, these things, we are all good students to control the amount, you record well, how many catties each piece is this time! You have to be aware that numbers are very important in practice and in production! ”

The students all nodded in understanding, found the corresponding things in a pre-made form, and awkwardly filled them out.

If you don't understand, you will personally ask Yan Zheng, and you can get a very patient answer every time.

Yan Zheng will also take the trouble to remind them that there is a leak.

After the mud is mixed, the bottom of the outer mold is first paved with mud, and then put into the inner mold.

Then, the gap between the two layers of molds is filled and compacted, just like the clay blank used to make a large clay jar.

The next step is to dry the crucible blank over a slow fire and send it to the kiln for firing. The crucible that burns paper also needs to be brushed with a layer of iron oxide glaze on the surface, which is the slime of iron colonies.

Yan Zheng made five crucibles in one go, almost using up four hundred catties of graphite, and he planned to use the rest to test it slowly, and he didn't dare to use it all at once.

The biggest advantage of graphite crucible steelmaking is that, unlike open-hearth steelmaking, it has high requirements for regenerators. It does not build a regenerative chamber and does not have a significant impact on steelmaking.

However, in the spirit of the mentality that there are no difficulties to create difficulties, Yan Zheng still had people build a regenerator, the purpose of which is to reduce energy consumption first, and secondly, to cultivate these understandings of the integrity of steelmaking.

Five days later, Yan Zheng made steel from the crucible for the first time.

He first added pig iron and roasted steel to the crucible, then quicklime and some sand, and some bauxite.

Bauxite can be added or not, but it can reduce the melting point of iron, making the iron melt faster.

The iron wood needle was watching from the sidelines, and he really wanted to ask the Divine Son, can this really make better iron?

According to his experience as a skilled blacksmith, this is still done with a hammer, which does not seem to be much different from the previous iron-making.

It's just that he heard Yan Zheng say that these crucibles can directly produce steel!

Not long after, five crucibles had been placed in the smelting furnace, and Yan Zheng introduced: "You have all seen it! Next to this is the regenerator, through this device, you can use the exhaust gas to a certain extent, and the purpose of our blast is to increase the furnace temperature, and the regenerator is to ensure that the temperature is higher when the blast is blown! ”

Yan Zheng explained it to the students, and then asked them to light a fire.

After the fire is burned, the blast has already begun, and the heating rate is relatively slow due to the relatively simple regenerator and the beginning of heat storage.

When the flame turned orange, Yan Zheng asked them to close the furnace door and told the students who came to practice: "The flame is this orange-red, which means that the temperature has reached 1,000 degrees!" Temperature is a measure, you should remember, right? The reason why iron turns from stone to something like water is because the temperature reaches its melting point! ”

Yan Zheng, the people's teacher, seized every opportunity to educate his lovely students.

Although most of these students were confused, they also remembered that iron smelting requires temperature.

Almost two hours later, through the observation hole, it was already possible to see that the molten iron in the crucible was boiling, and a very dazzling bright light appeared. From time to time, blue flames come out to indicate that the carbon in the iron is being reacted away.

Yan Zheng smiled with satisfaction and said, "Open the furnace!" ”

Ironwood Needle and a few of his men made a few rounds around the stove, and after some prayer, he opened the door of the furnace, and suddenly a wave of heat rushed out.

Yan Zheng asked the ironwood needle to use a long spoon to get out the slag floating in the crucible.

Because the density of these slags is smaller than that of molten iron, all of them float on the surface of the molten iron, generally calcium phosphate and calcium sulfide, which are also the reasons for the brittleness of iron.

Therefore, in the Ming Dynasty, there was a saying that the Northern Iron was inferior to the Fujian Iron and the Guangzhou Railway, and the reason was that the North used coal to make iron on a large scale.

Later, Yan Zheng asked several blacksmiths to start stirring with a long iron chisel, which was to accelerate decarburization. When the stirring is done, the door is closed.

After waiting for about half an hour, Yan Zheng asked the iron and wood needles to add the crucible.

Temu was very skilled at this work, and he cooperated with another man to clamp out the crucible with iron tongs, seemingly insensitive to the bright light and the blazing heat.

Then, under the command of Yan Zheng, they poured molten steel into a sand tank.

Yan Zheng immediately spread a layer of lime on the surface of the molten steel in the mold groove, and another layer of charcoal was spread on the lime to prevent it from oxidizing in contact with the air.

When it cooled, everyone gathered around to take a look at the steel plate.

Yan Zheng picked up a hammer and knocked it, and after slashing it a few more times, a satisfied smile appeared on his face!

The crucible steelmaking method - it's done!

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