Daqin Engineering Corps

Because most of the Xiongnu live on water and grass, they have neither the demand for arable land nor iron ore, so they don't have much interest in iron smelting technology...

In fact, the Huns have always relied on copper and tin from the Central Plains in terms of weapon production.

That is to say, they don't smelt it themselves, because they don't have the technical reserves for smelting and they also lack the knowledge of mining.

They usually use horses, furs, etc. to exchange copper and tin with countries in the Central Plains at the border, and then use them as raw materials to make the required weapons and equipment.

Therefore, Jia Yi, a famous scholar in the Han Dynasty, even suggested that Emperor Wenwen of the Han Dynasty control the outflow of copper and tin on the border of the Central Plains to weaken the Huns' combat power.

The idea was good: without copper and tin, the Huns couldn't make more weapons and could easily defeat them.

The problem is that it's basically impossible.

The reason is that the Xiongnu’s demand for copper and tin is there. If the Central Plains controls its outflow, the price of Xiongnu’s copper and tin will skyrocket... Originally, one catty of copper was exchanged for one horse, and one catty of copper was exchanged for two horses. even more.

And the high-quality horses of the Xiongnu are urgently needed in the Central Plains, and they can be sold at a high price immediately when transported to the mainland.

Driven by this huge benefit, unscrupulous profiteers and even common people in the Central Plains would go crazy and desperately smuggle copper and tin to the Xiongnu.

The end result was that the Xiongnu could still get the raw materials they needed, but lost more horses and furs.

As mentioned before, ironware in this period could only be used to make farm tools but not weapons, and the Huns did not cultivate land, so they had no interest in iron at all.

I have no interest in iron, and of course I have no interest in iron smelting technology.

Knowing this, Bian and Qiao thought that Shen Bing was making a big fuss by keeping the iron-smelting technology secret from the Xiongnu.

However, they soon found out they were wrong...

Shen Bing immediately handed Bian a few blueprints and said:

"Make the blast furnace into such a shape."

"The whole is flat and round, and the air blast is located on both sides of the flat."

"And the furnace wall at the lower part of the blast furnace is inclined 62 degrees outward..."

Ben was dumbfounded when he heard that:

"General, what is 62 degrees?"

Shen Bing let out an "uh", and then took out another blueprint to explain:

"We can divide the semicircle into 180 parts of equal size, and each part is one degree."

"In this way, the outward inclination of the blast furnace is exactly the same everywhere."

Benz understood what he was listening to, but he didn't know why he was trying so hard to do so. He just let out a confused "oh", and then looked at Xie who was standing aside with a look of pleading for help.

He thought he should spend more time with Shen Bing, so he would know more about these things.

I didn't expect that owed is also a puzzled look.

Of course they don't know why they did this, these are the iron-smelting techniques of the Han Dynasty.

Needless to say, why the blast furnace is made into an ellipse is to blow air into the furnace core, so that the temperature in the furnace can be increased and the carbon in the molten iron can be oxidized as much as possible.

As for tilting the furnace wall at the lower part of the blast furnace outward, it is for the coal to fully burn...

In the case of limited wind, the combustion of oxygen and coal in the blast furnace will produce combustible gas.

If the lower part of the blast furnace is not tilted outward, the gas will be quickly discharged along the updraft of the furnace wall, which is not only a waste but also pollutes the air.

The inclination of the lower part of the blast furnace will change the internal air circulation mode and increase the contact area between the gas and the charge, so that the gas will be burned in the furnace.

Of course, Shen Bing couldn't explain these things to Bian and Qiao, especially since the ancients took hundreds of years of practice to sum them up, and Shen Bing couldn't explain them clearly even if he wanted to.

So he pretended not to see the confusion on Bianhe's face, and asked:

"But is it difficult to make a blast furnace of this shape?"

Ben and Qiao hurriedly answered:

"Go back to the general, there is no difficulty."

"The subordinates will definitely make it properly according to the general's request."

This is indeed not difficult. If you can make a round blast furnace, you can naturally make the blast furnace that Shen Bing requested. It just changed its shape.

In addition, Shen Bing also asked people to find limestone...

The problem with using coal to smelt iron is that the coal has too many impurities. If it is smelted in this way, although it can be mass-produced and the carbon content of iron can be reduced, the sulfur content will rise sharply, resulting in little improvement in the quality of iron.

Limestone was added to solve this problem.

In addition, a large amount of slag is produced in the process of iron smelting, which contains a large amount of silicon dioxide, which will cause the slag to be highly viscous and adhere to the blast furnace, which is difficult to remove.

After adding limestone, silica will react with calcium oxide to reduce the melting point of slag, making it easier to remove.

Naturally, the blower equipment uses water drainage.

It's just that there is no river in the barracks.

For this reason, Shen Bing also specially asked people to open a small canal from the Yellow River... This not only solved the hydraulic problem of water drainage, but also solved the problem of water use for iron smelting.

Out of caution, Shen Bing also sent soldiers to block the upstream and downstream of the canal with fishing nets and guard them day and night... If there is a river, it is easy to leak secrets. The information was passed on.

Once that's done, all that's left is to start smelting.

Chapter 297 Crossbow

Although Bian and Qiao didn't know why, they still followed Shen Bing's request meticulously... No way, who made Shen Bing the boss?Do whatever the boss says.

A week later, after the first furnace of molten iron came out, Bian felt a little different... People who have been smelting iron for a long time like Bian can feel the change in the quality of the molten iron just by looking at the flow rate, consistency and solidification time, even if it is extremely Tiny bit.

After the iron ingot was solidified, Bian stepped forward with a hammer and hit it with a small force at first, but then it became more and more frightening at the same time.

If it were the iron ingot from the past, it would have cracked and then shattered by now, but the iron ingot in front of him was only slightly deformed after being struck with several times the force.

The other blacksmiths also realized that something was wrong when they heard the knocking sound, and surrounded them one after another.

Then I tried a few more people to come forward and knock, and finally cracked the iron ingot with the strength of nine bulls and two tigers.

All the blacksmiths, including Bian and Qiao, cheered excitedly. Bian even burst into tears, and said excitedly to Shen Bing:

"General, my subordinates have been looking for this kind of iron smelting technique all their lives, but they can't get in."

"I don't want the general to get this iron by simply modifying the blast furnace. The subordinates really admire it."

Qiao also cupped his hands and sighed:

"It's no wonder the general wants me to keep it a secret."

"As soon as this iron is produced, weapons and even armor can be made from this iron. It is not difficult to imagine that it will be much stronger than bronze."

"This law really cannot be known to outsiders."

I owe it to the point.

Once iron makes up for its brittle and easy-to-break shortcomings, bronzes will be completely eliminated because of its advantages such as simple manufacturing process, cheap and strong, so the importance of iron will naturally rise extremely rapidly.

In fact, this is not a sophisticated technology.

If it is just to reduce the carbon content in iron, blacksmiths in the Warring States Period can already do it.

Iron in this era is divided into pig iron and wrought iron.

Pig iron is hard, wear-resistant, and castable, but brittle and easy to break, which is the characteristic when the carbon content exceeds [-]%.

Wrought iron is soft, has good plasticity, and can be drawn, but its hardness is not enough, which is a characteristic of the carbon content of less than [-]%.

The method of making wrought iron is to reheat pig iron to 1500 degrees to reach the melting point of iron, and then use tools to continuously stir.

In this way, the carbon in the molten iron will be oxidized and discharged due to contact with air, and finally wrought iron will be obtained... This process is like boiling pig iron, hence the name "wrought iron".

The carbon content of steel is between pig iron and wrought iron, so it has the characteristics of pig iron and wrought iron.

The iron smelting method of the Han Dynasty used by Shen Bing is to further reduce the carbon content in the case of producing pig iron, so that its characteristics are closer to the direction of steel, which meets the requirements for making equipment and weapons.

Of course, it's just "meets the requirements".

If you want to get higher quality weapons, you need to make steel instead of iron.

However, this iron is completely enough, especially at this time when all the equipment in the world is bronze, iron equipment is enough to form an advantage over it.

Then he asked:

"General, after we have this iron, what should we make first?"

This is a problem.

Is it an iron sword, a shield, or spear armor?

Equipment must come first, first served. After all, the production of iron was limited at the beginning and the time was also limited. It was impossible to make them all in one go.

After thinking about it, Shen Bing replied:

"Crossbows, and arrows."

Hearing the words, he couldn't help but wonder:

"Crossbow? Made of iron?"

Oddly enough, crossbows are usually made of wood or bamboo.

Iron crossbows were impossible before this. It is difficult to make iron into a thin crossbow arm, and it is brittle and easy to break, and it may break after a few strokes.

But now it is possible to use iron to make crossbows...

But Shen Bing didn't think so for the time being.

He shook his head and said:

"It's not a crossbow, but an iron ring is added to the front end of the crossbow arm for stepping on."

Bian didn't quite understand what he heard, so he let out an "oh" and nodded in praise:

"The general is wise, this method is very good!"

At this time, the Qin army... It should be said that the crossbows of the countries in the Central Plains are divided into two types: arm-stretch crossbows and kick-stretch crossbows.

Both have pros and cons.

As the name suggests, arm-stretching crossbows are opened by hand, and their range is not much farther than that of bows and arrows. Sometimes, the range of crossbows is not as good as that of bows and arrows because of the shortness of crossbows and straight ballistics.

Its advantage is that it is convenient to open the crossbow, the rate of fire is fast, and it can be completed by hand. The cavalry in the Central Plains prefer to use the arm crossbow to make up for the lack of riding skills.

Infantry is more likely to use kicking crossbows.

Because for infantry, it is better to choose bows and arrows if you choose arm tension crossbows... The shooting speed of bows and arrows is stronger than arm tension crossbows, and the range is not far away.

But there is another fatal shortcoming of kicking the crossbow: you have to sit on the ground to open the crossbow.

The standard method of opening the crossbow is to sit on the ground and use both legs to touch the concave part of the crossbow, one on the left and one on the right, and then pull the string with both hands to prop up the crossbow and stick it on the crossbow machine with the strength of the waist.

This has to be done every time after firing, so the crossbowman usually sits on the ground to operate.

This is no problem when defending the city, but it will cause big problems when attacking the city or in field battles.

Especially in field battles...you have to sit on the ground and fire the crossbow. What if you want to chase the enemy after winning the battle?

Or what if you lose a battle and want to retreat while fighting?

It's impossible to suddenly sit on the ground and fire a crossbow while chasing down the enemy or retreating, right?

This will not only slow down your own speed and block your comrades, but also slow down the speed of the entire army.

Therefore, crossbowmen have almost no combat effectiveness in action, and cannot maneuver when they have combat effectiveness.

There are many other issues besides:

For example, the field of view is not high when sitting, and it is easy to be blocked by your own people. At the same time, compared with standing and launching, the shooting range is also greatly reduced.

Another example is that you have to sit and open the crossbow when it rains or snows... Although this can be overcome most of the time, it is fatal in some special cases. For example, in the extreme cold conditions in the north, if you sit on the ground, the armor will I am afraid that I will be frozen and unable to get up.

But it would be different if a step ring could be added to the front end of the crossbow arm.

Because of this change, the crossbowman can stand and operate:

Stepping on the ring with both hands to buckle the string, also using the waist force to stretch... the crossbow opened.

Almost all the disadvantages of the old-style crossbow are thus avoided:

It is easy to maneuver, easy to shoot, and the rate of fire is also accelerated.