About 500 meters away from the gunsmith is the cannon foundry, where the cannon, the god of war, is manufactured. The cannon says difficulty. In fact, it is not very large, such as the Tiger Squat Cannon, as well as some small-caliber artillery in the West, which can be manufactured under the guidance of Zhu Houwei.

However, there are also big problems, there are two main ones, one is that the current cannons are made of copper, and the Ming Dynasty lacks copper, which is very short, because the main currency Hongzhi Tongbao is cast with copper. However, due to the lack of copper, the value of copper coins was far inferior to that of copperware, and although the imperial court stipulated that bronze could not be minted privately, it was not prohibited at all. In many places, there are people who dissolve copper coins and make copper utensils to make huge profits.

Under Zhu Houwei's assumption, Daming will need a lot of cannons in the future, and if copper is used, it will be a big burden for Daming, and even more so for the two brothers.

For example, the relatively small, suitable for close-range field battles, has a range of only 7,80 meters, but such a small cannon costs nearly 200 catties. In the future, if you organize a fleet, a battleship will have to carry 100 or even 200 cannons, how much copper will be needed. The navy wants artillery, and the army is also indispensable, and 3,000 infantry basically need to be equipped with more than 100 artillery pieces of various types, so how many artillery guns does the army need alone.

Therefore, Zhu Houwei decided to cast steel cannons. As long as the steel quality is good, it is definitely much lighter than the heavy copper cannon, and many relatively large caliber cannons can also be used in field battles.

Now, the military factory already has a steel plant, and the quality of steel is slowly increasing, after all, the smart Chinese are not our self-appointed, that is the world's research and recognition.

Now the biggest problem is the casting method, the Ming Dynasty is now using the clay mold casting method, most Western countries are also like this, but the yield is very low, only 2 to 3 of the 10 cannons are qualified, this is not a phenomenon only in the Ming Dynasty, the whole world has this data.

Even if steel is used now, the success rate is so low that it really costs a lot to build a qualified cannon. At present, a pound of iron costs a penny of silver, and 10 catties is a tael. Even if the smallest tiger squat cannon is to be made, 1 gun will cost 100 taels, which is only the price of iron, not counting other materials and labor. Basically, it will cost 150 taels and 1 door, and if it is larger, it will cost 1,000 taels, or even 10,000 taels.

For this data, Zhu Houwei has a headache. Because in the future, a big gasp will cost 50,000 taels, and 100 cannons will be placed on it, and 2,000 taels will be one, then the cannon will cost 200,000 taels, and a warship will cost 250,000 taels, and several can be built with the current assets.

So Zhu Houwei began to work the method of cannon casting. Originally, Zhu Houwei wanted to use the iron mold casting method invented by Gong Zhenlin in the Qing Dynasty. In the past, when I read novels, this method was very good, because this casting method can increase the yield rate from 20 to 30 percent to 70 to 80. Later, Zhu Houwei went to look up the information to see if this method was so good.

After various channels of information and discussions with friends on the Internet, I found that this method is not so godly.

The iron mold technology is not difficult to do in its own hardware, cast iron or cast steel can be, it is nothing more than a bearing container, and the role it plays is better than heat dissipation in addition to fixing the gun mold.

The advantage of the iron mold is that it is easy to integrate, unlike the clay mold casting cannon, which has to wait for time to dry. These hardware Ming Dynasty can be fully realized.

However, there are also shortcomings of the iron mold, from the point of view of metal casting and metallography, the heat dissipation of the iron mold is too fast, so that the pig iron liquid has a large degree of supercooling when cooling, and the cementite in the molten iron has not had time to precipitate (graphitization has not had time to carry out) The graphite has solidified, so the cementite in the iron mainly exists in the form of iron carbide, that is, white iron.

Of course, due to the large degree of supercooling of the molten iron during the solidification process, the metal crystalline particles on the surface are relatively dense and the body tube is relatively smooth;

The only benefit of the iron mold is that it speeds up the production rate and does not have to wait for months like a clay mold cannon. However, the whitening of the products of the iron mold cast cannon is very serious, because the cooling speed is too fast, although it is relatively smooth, but almost all of the white iron is generated, resulting in an increase in brittleness and a decrease in the performance of the gun. In order to increase the tensile strength, it can only be solved by stacking the mass by quantity, that is, by increasing the wall thickness. According to statistics, almost all the newly cast artillery in the ** war was white iron! It is also reasonable to analyze it from the perspective of metallography.

The problem to be solved now is how to make the white iron still gray iron after cooling, and only the gray iron can withstand the huge bore pressure.

When he arrived at the foundry, the person in charge, Zhou Qingshan, walked in front of the Zhu Houwei brothers with a shameful face. Zhu Houwei knew that casting cannons was very difficult for all craftsmen of this era. When he arrived at the artillery factory and saw the scrapped artillery all over the ground, Zhu Houwei sighed and said to Zhou Qingshan and Yan Yuese, "Old Zhou, don't be ashamed, it's already good to be able to make the cannon." As for the cannon casting process, it is indeed a very difficult process, solve it slowly, don't worry, just pay attention to safety. ”

Zhou Qingshan also dug it from the Ministry of Industry, and now he has 80 taels of monthly money alone, and he can basically get 1,000 taels a year. But with such a high monthly money, he couldn't meet the requirements put forward by Zhu Houwei at that time, and he was always ashamed in his heart. Even if Zhu Houwei was comforted now, Lao Zhou just kept nodding, but the shame did not dissipate.

Zhu Houwei thought about it, and finally decided to solve these problems together with these craftsmen.

From today onwards, Zhu Houwei went straight to the military factory every day out of the palace to solve the problem of cannon casting technology.

The first is to make gray iron. Zhu Houwei asked the craftsmen to build metal hot air ducts and regenerators first, so that even with hot blast technology, it would be of great help to increase the furnace temperature. Then the iron and coal purchased by the military factories were refined. In this way, when the molten pig iron is cooled, the fracture is still gray iron.

Then the iron mold casting method is used when casting the cannon. Gong Zhenlin's iron mold casting method in the Qing Dynasty was to make a hard mold from iron. When casting the gun, first brush the inside of each petal of the iron mold with two layers of slurry. The first layer of slurry is made of fine rice husk ash and fine sand mud; The second layer of slurry is made of fine kiln coal and water. Then, the two petals are combined, tightened with iron hoops, baked, and continuously continued, and finally the molten metal is cast. After pouring enough molten liquid and cooling and forming, the iron mold is immediately peeled off according to the order of the mold flaps, like peeling off the bamboo shoot shell, and the gun body is gradually exposed, and then the mud embryo in the gun core is removed, and the chamber is naturally smooth.

Compared with the traditional clay mold casting cannon, the advantage of the iron mold casting cannon is that the cast cannon body is of good quality, and the inner and outer surfaces are smooth, unlike the clay mold, which will make the cannon body produce bubbles. In addition, because there is no need to painstakingly apply clay molds and other drying, the manufacturing speed is fast and not affected by the weather. Because the mold can be reused, the production speed is fast, the output is large, and the cost can be very low. The greater significance lies in standardized manufacturing. Standardized manufacturing is essential for artillery to produce products that are almost identical in shape and performance.

This iron mold casting method is 30 years earlier than that of the West, of course, this is also related to the different development directions of the Eastern and Western processes. The East is still mainly committed to the traditional hand-made cannons, while the West is developing mechanical manufacturing.

In the first month, the gray iron was made, and then the cannon was cast. But Zhu Houwei calculated the recent expenditure, just to improve the ironmaking process, to produce high-quality low-carbon steel and high-carbon steel spent 100,000 taels, this speed of spending money made him feel terrified. There is also an experimental cannon making in the back, which is not a small project. Zhu Houwei couldn't help but sigh, "Where is the money, why is it so easy to spend?" ”