Xia Nan asked: "Then what's so good about the gray iron?" ”

"White iron is too brittle, easy to blow up, and high hardness, wear-resistant, not easy to process, resulting in rough and uneven inside the gun body and gun chamber, in order to launch the shell smoothly, it is necessary to make the diameter of the shell far smaller than the barrel caliber, so that the clearance between the shell and the barrel is too large, the air tightness is poor, and the power, range, and accuracy are greatly reduced. Pen | fun | pavilion www. ｂｉｑｕｇｅ。 The carbon of info gray iron exists in the form of flake graphite, the fracture is gray, the shrinkage is small when solidified, the compressive strength and hardness are close to carbon steel, and the shock absorption is good. Due to the existence of flake graphite, it has good wear resistance, good casting performance and cutting processing, and graphite has a lubricating effect on the tool. ”

Lin Weiye thought for a while: "In the words you can understand, gray iron has the advantages of hard and wear-resistant white iron, but there is no disadvantage, the cannon cast with it basically has no cracks, moderate brittleness, not easy to explode, the most important thing is that it is easy to process, the cannon can be cut with a tool is very smooth, the clearance between the gun chamber and the shell is reduced, the diameter of the shell can be close to the caliber of the barrel, the air tightness is very good, the power, range, and accuracy are far greater than the cannon made of white iron." So, can you understand? ”

Xia Nan rubbed his swollen head, "Am I right to understand it this way: although the cannon cast in white iron is hard, it is very brittle, easy to explode, and it is not easy to process, it is very rough, it is easy to leak air when firing guns, it is small in power and has a short range, and it is not accurate to hit; The cannon cast in gray iron is completely opposite, hard but not brittle, very durable, will not blow up, and easy to process, will not leak, powerful and long-range, and accurate? ”

Lin Weiye high-fived and applauded: "It's completely correct, the comprehension ability of high-achieving students is really not covered." ”

"In that case, why not get a gray iron? What are you talking about here? Xia Nan was puzzled.

Lin Weiye sighed: "How can it be so easy, if it were easy, the Qing Dynasty would not have used white iron to cast cannons during the Opium War." High-quality gray iron was not produced in large quantities until the 19th century, and Europe was dominated by bronze cannons until the Napoleonic period. ”

"I've heard that copper cannon was the best material for cannon casting when the ironmaking industry was not developed, but copper was very expensive and not cost-effective. Then again, does Qiongzhou produce copper? ”

"The copper production in China as a whole is not too high, and there are associated copper mines in the Shilu Iron Mine in Qiongzhou, but the output is not high. Moreover, in ancient China, copper was a precious metal, which was used to make coins, and the price of one copper cannon in Europe was equivalent to five identical iron cannons, and in China it was far more than that. Use copper to cast cannons, you capitalist are willing to do it? Lin Weiye teased him.

Xia Nan naturally objected: "Reluctantly, I don't do loss-making business." ”

However, there is another reason why Xia Nan didn't say it, he has a long-term plan in mind, copper is a strategic material, a precious metal linked to currency, and it is a heavenly thing to use to cast cannons. Now the time is not ripe, this plan will not be told to Lin Weiye for the time being.

Lin Weiye didn't know his little abacus, just did further technical analysis.

"The key to gray iron is silicon, the silicon content is greater than 1% to get gray iron, less than 1% is white iron, and the furnace temperature is the key to reducing silicon, the furnace temperature is lower than 1500 degrees can not get gray iron, and the traditional charcoal ironmaking furnace temperature will not exceed 1300 degrees, and the only thing you can get is white iron."

Summer Nan pointed to the crux of the problem, "So how to increase the temperature of the furnace?"

Lin Weiye thought about it carefully, he tried to remove the modern steel production line from his mind and replace it with a 17th and 18th century blast furnace, and after considering various factors, he cautiously answered Xia Nan's question.

"Since there is no steam engine, the way to increase the temperature of the furnace is to replace charcoal with coke, build a regenerative chamber, replace the steam engine with hydropower, and use preheating blast technology, which should be able to obtain gray iron with a higher silicon content. Technical problems such as regenerators and air blasts can be slowly overcome through practice, and the problems are not big. ”

"But the problem of coke is more troublesome, and Qiongzhou only produces lignite, which is an inferior coal with a very low degree of coalification, which is not suitable for coking. Bituminous coal is generally used for coking, China's largest bituminous coal production area is in Shanxi, but it is too far away from us, among the coastal provinces, only my hometown Shandong has a considerable bituminous coal production, but it is still beyond our reach, the Ming Dynasty cannot let us mine coal, there is still the hinterland of the imperial court, very close to Beizhili. ”

Xia Nan had all his thoughts: "You are in charge of the technology, and the implementation is left to me." However, are you sure that you have to go so far to Shandong to dig coal? ”

Lin Weiye spread his hands: "Guangdong also produces coal, but the reserves are too small, and it is not a shallow mine, with our technology, it cannot be explored." There are several coal mines in Shandong that are shallow mines that are easy to explore and exploit, so ......"

Xia Nan clapped his hands and said: "Understood, Shandong's affairs can be included in the long-term planning, let's talk about the present, can't you cast cannons without coke?" Without Zhang Butcher, do you have to eat hairy pigs? ”

"In fact, there is also a way, which is to graphitize and anneal the white iron. That is, after slow heating, it is controlled to cool at a certain speed, and malleable cast iron can be obtained, which is called malleable cast iron by Europeans, which has better plasticity and toughness than gray cast iron, and the hardness and toughness are close to high-quality carbon steel, and it is better to process than steel......"

Summer Nan was messy: "I'm a little messy, let me pick it up." Do you mean that that kind of garbage white iron can be better than gray iron and close to the characteristics of steel if you burn it casually? Oh my god, then why are you bothering your old nose to make gray iron? ”

Lin Weiye felt very aggrieved, and explained to the layman that it was so troublesome: "Although the malleable cast iron obtained by this method is good, it has great limitations in implementation, and it is limited to relatively small and simple castings, and the wall thickness cannot be greater than 100 mm, generally about 80 mm." First cast with white iron, and then put into a large processing furnace to simmer, the annealing time is very long, the efficiency is not high, just a transitional method before the appearance of gray iron. This method cannot build naval heavy artillery, but small-caliber field artillery is still possible. ”

"I'll go, I'll be happy in vain, and my feelings can only make a small cannon." Xia Nan expressed contempt.

He sorted out and summarized Lin Weiye's words, making guns - you can use the existing steel frying technology, making cannons - it is possible to cast heavy cannons with coke, and at present, you can only cast small cannons. The top priority is to solve the problem of whether there is or not, and then we have the energy to solve the problem of heavy artillery. As for the current long time and low efficiency of casting small cannons, it is not a big problem, they can wait, and with the guns, they can deal with most of the opponents they can meet now.

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The following has nothing to do with the text.

The book was signed very early, and it was less than 10,000 words when the contract was sent, and the time for streaking was relatively long. In the two weeks of streaking, I would like to thank my friends 15255402692, Lingyuxuan, No Return Period, and Nightmare Return RDR1 for always voting for me, and your support is my motivation.