Xu Qiu's brain was spinning.
Could he change the commonly used Ferrite steel to Austenite steel?
His eyes lit up.
Ferritic steel had a body-center structure, while the steel had a face-center structure.
The metal displacement of the body-core structure was rather special. In the direction of the body-core structure metal, the atoms themselves were also arranged in a spiral.
Therefore, when the steel with this structure was misaligned, it would either be the addition of the two spirals or cancel each other out, which would bring about two different energy states!
The result was that when the " dislocations " tried to slide, the positions with high energy would become obstacles to the sliding, making it difficult for the dislocations to start, and it would be more difficult for the " dislocations " to occur!
However, the Austenite steel with a face-center structure did not have such a characteristic at all. It could maintain a sufficiently high toughness at low temperatures!
Thinking of this, Xu Qiu understood and said,""Austenite steel it is!"
Austenite steel had a very high low temperature toughness, and generally did not have a toughness-brittle transition temperature!
"Austenite steel can be designed into three types of alloys.”
"The first is the Fe-CrNi alloy. This type of low-temperature toughness, corrosion resistance, and workmanship were relatively good. It should be able to be used in various cryogenics!”
"The second type is the Fe-CrNi-Mn and Fe-CrNi-Mn-N systems.”
"The third type is the Fe-Mn-Al-type.”
……
Zou Botao wrote down all the steel materials Xu Qiu mentioned.
"Chief Xu, what's the second point?"
Xu Qiu sipped his tea and said," Other than the toughness under low temperatures, it must also meet the strength of construction fifty to a hundred meters underground!”
" After the sun goes out, there will be continuous snowstorms. The layer of snow on the surface will become thicker and thicker, and the weight on the main structure of the Buried City will increase!”
"Therefore, this kind of steel also needs to have extremely high strength!”
"Third, at a low temperature of-200 degrees Celsius, this material needs to maintain its structural stability.”
"Fourthly, it has good welding and processing properties.”
" The construction of the Buried City will only take a year. We have to complete most of the structure within a year. Otherwise, when the sun goes out and the soil freezes, it will be impossible to start construction!”
"Therefore, the difficulty of processing this steel cannot be high.”
"Fifth, it needs to have extremely low magnetic conductivity and cold contraction!”
Xu Qiu closed his eyes, and his mind was constantly filtering the Austenite Steel.
In the end, the Fe-CrNi-Mn-N series Austenite Steel stood out!
Due to the addition of nitrogen, the strength of this type of steel would increase. More importantly, it had extremely low magnetic conductivity!
Especially 0Cr21Ni6Mn9N and 0Cr16Ni22Mn9Mo2,
Even at an ultra-low temperature of-269 degrees Celsius, it could be used as a non-magnetic structural component!
Xu Qiu's eyes became deep.
In the next year, this type of Austenite Steel would become the most eye-catching construction material in the Super Dungeon!
……
……
Raspberry Country.
Although they did not know what the Dragon Country was going to do, the president and the others decided to send a team to follow the footsteps of the Dragon Country and build an underground city.
Dozens of world-class geologists, physicists, and architects gathered in a suburb of New York.
This was the most suitable place to build an underground city after they had surveyed dozens of cities.
However, after a few days of discussion, the top scholars finally came up with a final plan.
On the first day of construction, they encountered a series of troubles!
Rock mechanics expert Wendy said in puzzlement,""The construction of a Dungeon is based on the theory of rock mechanics. However, our discipline has only been developed for more than a hundred years. It was not until the 1990s that we had a systematic rock mechanics system!”
" It can be said that the current development of rock mechanics is very immature. We have placed too much emphasis on the ideal state, oversimplified the calculations, and relied too much on experience.”
"Moreover, the theoretical knowledge of rock mechanics is not complete enough to support practice!”
The geologists present were also silent.
They felt that building an underground city was simply a fantasy.
" Most rockworks can't be done in one excavation," said architect John Xun. Due to the non-linear nature of rock materials, their state after being subjected to force had a loading path, so every excavation would have an impact on the next excavation!”
"The construction sequence is different, and the excavation steps are different. They all have different final mechanical effects!”
" The impact of each excavation is complicated and uncertain. With the current theories, it's not a problem to support an underground parking lot, an underground commercial street, or a subway, but…the underground city, God will not allow us to do this!”
" Yes." Wendy nodded in agreement. "I don't know how the Dragon Country did it, but if we want to build an underground city, we need to have a deeper understanding of rock mechanics. We need a more systematic guiding theory, a greater computing power, and more accurate surveying technology!”
" There's also a more rigorous construction method, more advanced machinery, and a richer…material foundation!" John added.”
These scientists, whose academic achievements were much higher than those of the Dragon Country, were standing at the construction site at this moment, at a loss.
They could not imagine what gave the scientists and construction workers of the Dragon Country the courage to dig into the core and build an underground city…
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