Qi Zu was not on the open-hearth construction site, and this thing was successfully developed at the end of last year, which is not a new thing. Hong Tao was overseas at that time, and he didn't know when he would come back, so the board of directors overstepped his authority to approve Qi Zu to build a 2-ton open-hearth furnace to try, if it was successful, wait for Hong Tao to come back and then ponder whether to build a bigger one.

"Premier Hong really forgot to sleep and eat, I didn't believe it when you said you didn't want to be the emperor before, but now I really believe it, this emperor is really not a human being. You've only been back for three months, you've lost 20 pounds, and your chin is pointed. It wasn't until he slipped to the foundry that Hong Tao saw Qi Zu, who was standing in front of a pile of things covered with tarpaulin, and after meeting, he didn't talk about business, but joked first.

"Calling me early in the morning to care for my body? What's behind you? Qi Zu is a person who is not very good at communicating, and this kind of polite words coming out of his mouth can only show one thing, that is, he is in an extremely good mood, so good that his personality has changed. There is only one possibility that he can be so happy, that is, he has overcome another problem and made a finished product, which is to show off like Hong Tao.

"Hey, hey, hey...... Good thing, with it, we don't have to worry about whether the copper mine is enough or not! Come here, get ready for the test! Qi Zu mysteriously pointed at the pile of things behind him, and did not answer Hong Tao's question, but called a few workers.

"Iron Cannon!" As soon as the tarpaulin was halfway opened, Hong Tao was taken aback, and under the tarpaulin was covered with a gun carriage, on which lay a cannon. This cannon is different from the past, it is not the yellow of alloy copper, but black.

Bronze cannons and iron cannons are both cannons though. But in terms of technical process, it is much worse. It was not until the eighteenth century that the well-established art of casting iron cannons began to gain popularity. Bronze casting cannons were available at the end of the 14th century, a difference of three or four hundred years. With cast iron cannon technology, the production cost of artillery will be greatly reduced, and it also means one thing, that is, the yield will be very high. Because the process of casting cannons with iron is different from that of copper casting, if you master this process, the yield will inevitably rise, and it is not a star and a half. This is a technological revolution that spans centuries.

"Yes, even with the kind of internal cooling technique you said, it's weird, let the cannon body cool itself and it won't be strong, there are a lot of bubbles, add a water pipe to it, the cannon body is tighter and tighter the inside, and there are fewer bubbles." Qi Zu kept saying that the experiment was successful according to Professor Hong Tao's method, but the pride on his face was not suppressed at all. Indeed, on these jobs. Hong Tao also gave them a wake-up call and pointed out a direction, and 99% of the actual work was completed by them. These achievements are something to be proud of.

"Well, the annealing is good, is it heated and cooled with water?" The internal cooling technique mentioned by Qi Zu should actually be called the inner membrane controllable cooling technology, which is closely related to Hong Tao's profession, although he has not really played this technology, but he knows much more clearly than smelting, forging, and chemical engineering.

The disadvantage of casting cannons with cast iron is that molten iron does not flow as easily as molten copper, so bubbles can easily form during the casting process. And in the process of natural cooling, the outer layer of the gun body will be cooled first, and the inner layer will be cooled last, which is affected by the overall uneven heat and cold, and the inner wall of the barrel after cooling is likely to be uneven or even large holes. In addition, due to the poor workability of cast iron, if the inner wall is too uneven, this barrel will be scrapped.

Even if it is not scrapped, the barrel structure cast in this way is not ideal, its outer texture is very tight, the more it goes inside, the looser it becomes, and the chamber pressure is slightly higher, it is easy to explode. At first, when Britain and France cast iron cannons, it was because of this problem that they had to cast iron cannons thicker than copper cannons, so that copper was saved, but the weight of iron cannons not only did not decrease, but also heavier than copper cannons, and the size was also large, and the safety was poor, and no one was willing to use it.

It was not until the American Civil War that this problem was perfectly solved by an artillery major named Thomas J. Rodman in the Union Army, so this casting method is also called the Rodman method. It is said that the life of the iron cannon cast by the Rodman method in the US federal army was increased by more than five times, and the most surprising thing is that the cannon cast by this casting method has a very low scrap rate, as long as there is no mistake in the operation, there is almost no scrap!

Major Rodman's method was simple: replace the mold in the center of the barrel with a hollow steel mold and connect a water pipe to it. When pouring molten iron, the inner wall of the barrel with circulating water through a hollow steel pipe is first cooled. As we all know, the specific heat of water is much greater than that of air, so water also cools much faster than air. The inner layer of the scorching gun body must be contracted when it is cold, but the outer layer is still hot, which is equivalent to cooling down layer by layer from the inside to the outside. Now we use the common sense of physics, that is, the heat expansion and cold contraction, the inner layer shrinks first, and then the outer layer shrinks inward layer by layer, after all the cooling, the more dense and smooth the barrel is to the inner layer, and a little boring is a good cannon. Moreover, the use of this casting method can greatly increase the strength of the barrel, and the barrel can be thickened without playing with life, and the iron cannon can not only achieve the same safety as the copper cannon, but also will not be heavier than the copper cannon.

Of course, this is only a rough principle, and it is certainly not so simple to do, and the most troublesome thing is the water cooling speed. If it's too fast, the cast iron will still crack, so how fast is fast, and how slow is slow? This requires constant experimentation. In order to figure out these data, Major Rodman experimented for ten years before mastering the mystery. However, Qi Zu only experimented for less than two years before he became proficient in this set, and even better than Rodman, and the iron cannon he forged was already gray cast iron. This thing Jinhewan can't be smelted yet, so how did he get it? Could he be more Rodman than Rodman?

At this time, you have to look here, isn't there a metal heat treatment professional Hong Tao! Playing with everything else is part-time, hobbies, and curiosity...... He is 100% professional in dealing with these problems related to heat treatment. How to solve the problem of water cooling too fast? It is easy to do, there are two ways, one is to control the water temperature, and the other is to control the mold temperature. The former did not have modern heating and pressurization equipment, and it was basically impossible to complete in the Song Dynasty; The latter is relatively laborious and expensive, but the technology is simpler, which is nothing more than to heat the outer mold and keep the temperature in the range of more than 200 to 300 degrees, without being too accurate. This technique is a blacksmith's skill, not to mention any thermometer, their skin is a natural thermometer, which can be accurate to about plus or minus ten degrees.

Another problem is that the flow of circulating water must be guaranteed, this problem is simpler, digging a well directly on the south bank of Jinhe Bay, must be dug to a depth of less than 10 meters, and then installed with hydraulic equipment to lift water. The well water is basically at a constant temperature, and it doesn't matter if the amount of water in a well is not enough, dig a few more holes and use them together. To cool a 155-caliber and 15-diameter gun, it takes about 150 tons of well water, and dozens of people need to constantly pour it into the steel touch with a simple hand pump. The whole process lasted forty hours before the cannon was cooled. At this time, due to the slow cooling rate of the cast iron, the stone mill in the substrate can be completely precipitated, and the gray cast iron is naturally formed, which is equivalent to killing two birds with one stone. After post-machining, it is ready for test-shot detection.

More than forty hours? It's really not much, compared to the original casting method, it is simply fast, and the most gratifying thing is that the cannon casting is successful with this technology. If this set of processes is proficient, the output of two months can be as high as the previous year, and the cost is nothing more than well water and manpower. But the changes it brought were so great that the warships in Jinhe Bay no longer had to worry about the lack of cannons, no longer had to make the old man grin because of expensive copper mines, and no longer had to limit their guns to 155 caliber short-barreled guns. With this technology, the weight of the gun will be reduced, and the gun body can be lengthened accordingly, which will have the direct effect of hitting farther, flatter ballistics, and better accuracy.

The cast iron cannon cast by Qi Zu with the controllable cooling technology of the inner membrane has a very significant feature, that is, the appearance is very strange. Due to the tight structure and high hardness of the inner wall of the barrel, the first half of the gun body can be thinner, which can effectively reduce the overall weight of the cannon, and only the rear end of the ****** explosion can be thickened to ensure the safety of shooting. The result is a cannon like a bowling pin or a wine bottle, thin in the front and thick in the back, but very performant, at least at the level of the early nineteenth century.

In fact, this kind of cannon is real in history, called Dahlgren cannon, and its inventor is also an American, called Johann Adolf Dahlgren, and when you hear this name, you are a Germanic descendant! He was in charge of the development of the cannon at the Washington Navy Yard before the Civil War, and he made this bottle-like thing. Despite its poor appearance, it worked very well in practice, for which he became the commander of the US Pacific Fleet. Of course, the whole world does not know who Rear Admiral Dahlgren is, and those who have seen this cannon call it a pot-bellied man, because the back part of it is indeed round and round.

The main advantage of the Dahlgren gun is not the light artillery, its shape is more suitable for casting large-caliber heavy guns, when the United States fought the Civil War, the major general once cast a 380 mm cannon, specially used against the armored warships of the Southern Army. However, Hong Tao did not really intend to build a large-caliber gun by choosing this gun type, he also had another idea, which provided the basis for the production of rifled guns.

(To be continued.) )