The ones who came were old acquaintances, Pang Jianmin and Zhang Zhen. Their warship had not gone to sea and was parked at the port. After getting the news, the two came over in a car. A group of sailors were sitting in an old Jiefang car behind them and jumped on the submarine.
, it’s just a one-pass inspection.
However, luck does not come all the time. There are no torpedoes like last time. They just found some submarine equipment. Qin Tao was not very generous and just gave them to them.
However, the two did not leave. When they finished inspecting the submarine, although the sun had set in the west, they still walked around the shipyard and quickly fell in love with the batch of steel plates sent by Liu Minggang.
"Isn't this too thin?" Pang Jianmin couldn't help but said.
"Everyone is used to riding on big ships. Look, ordinary speedboats are actually made of steel plates of this thickness. The anti-smuggling speedboats we built for the customs are also of this thickness."
"That's different. The catamaran passenger liner to be built next must meet military standards." Zhang Zhen said.
Qin Tao smiled: "Of course I know, military standards, the quality is absolutely superb. I have a steel test report here, do you want to take a look?"
"The yield strength is 520 MPa, which is higher than our 945 steel. How is this possible?" Zhang Zhen was surprised when he first saw the report.
Yield strength is an important indicator for measuring steel. In professional terms, yield strength is the yield limit of a metal material when it yields, which is the stress that resists trace plastic deformation.
To explain in simple words, it is the strength of the material. For example, the yield limit of low carbon steel is 207 MPa. When the pressure exerted by the outside world is greater than this value, the parts made of low carbon steel will be permanently deformed.
If it is smaller than this, the parts will return to their original appearance after the external force is removed.
The greater the yield strength, the greater the material's ability to resist external forces and the higher its strength.
For ordinary civilian ships, two to three hundred MPa marine steel is enough, but warships must be stronger.
Back then, when the relationship with Lao Maozi was close, Big Brother exported specialized marine steel. After the relationship broke down, the country could only bite the bullet and engage in research and development on its own. First, it imitated Lao Maozi's marine steel and developed a batch, such as
We talk about steels such as 907 and 921, but these steels imitate the composition of Laomaozi and contain a large amount of nickel and chromium.
The Ural Mountains in Laomaozi are rich in nickel ore and chromium ore, but there are few in China. Therefore, domestically we need to develop nickel-chromium-free or low-nickel-chromium steel.
In the past few years, the domestic situation was complicated, and the quality of the steel produced was very poor, and even accidents almost occurred (the steel used in a certain submarine was unexpectedly unqualified). After entering the 1980s, domestic steelmaking companies began to spend a lot of energy on research and development.
.
First, the 390 MPa 907A steel was developed. Last year, the 440 MPa 945 steel with better seawater corrosion resistance and low temperature performance passed the appraisal. As for the models still under development, there is the 785 MPa grade VHD402 steel.
.(This steel passed the appraisal in 1993 and was named 980 steel.)
The ships currently being built by the Navy only use 440 MPa grade 945 steel, but here, a new type of steel with a yield strength of 520 MPa appears. How can we not be surprised? (It looks like 921A steel used in nuclear submarines.
The yield level is not low either, but I didn’t find much information, so I ignored it.)
Qin Tao secretly laughed in his heart, is this still high? This is already low enough, okay? Mingzhou Shipyard has limited technology after all, so after the AK-25 steel with a yield of 590 MPa was re-melted, only 520 was left.
MPa.
You know, even Varyag uses this kind of steel. (Except for the deck, which is 700 MPa AK-27.)
Hearing Zhang Zhen's suspicion, Qin Tao touched his nose: "Are you suspecting that the test report is fake? When we cut the steel, you can take a scrap and go to the department for appraisal."
"No, no, of course not." Looking at the seal of the professional testing agency on it, Zhang Zhen shook his head: "I just feel a little weird, where did you purchase it from?"
"Our Mingzhou Steel Plant." Qin Tao said: "The quantity of this batch of steel is not large, and it is given priority to our own use. If outsiders want to buy it, they will have to queue up."
Mingzhou Shipyard, there are not many of them? Pang Jianmin looked at the three whale-like submarines in the distance, and suddenly thought of something: "Could they be you?"
"Why not?" Qin Tao smiled.
Zhang Zhen also suddenly realized.
"If we don't use high-strength steel, we need to use aluminum to reduce the mass. If we use aluminum, the construction cost will soar significantly, and our contract will have to be revised."
This is another reason why Qin Tao uses high-strength steel.
Most speedboats like to be built with aluminum, including the anti-smuggling speedboats they purchased drawings from island countries. The design drawings are made of aluminum, so as to reduce weight.
However, the current Mingzhou Shipyard has no experience in using aluminum, and it is expensive. Therefore, Qin Tao temporarily used high-strength steel instead. Steel with a yield of 520 MPa is definitely better than aluminum.
use!
"No, no need." Zhang Zhen waved his hands quickly, never mention money, you can still be good friends without mentioning money.
"Well, then the contract will not be modified, but I hope your funds will be available as soon as possible. We will start construction soon. There are many places where money is needed, especially the two planned high-power diesel engines, which need to be ordered quickly." Qin
Thao still has to press for money.
How can we start work if we don’t have enough money?
"Do we have to buy those two main engines from abroad? Can we use the diesel engines of missile boats that we make ourselves?" Pang Jianmin asked.
"Yes, if we use domestic diesel engines, we can save a lot of money." Zhang Zhen also said at the side.
"Of course not." Qin Tao said: "Our domestic diesel engine is currently used on missile boats, the K48E150ZC two-stroke diesel engine developed by 711 Research Institute. Although the power reaches 5100 horses, it is equal to the Soviet M50-4
The power, however, is still not enough for my design specifications and cannot reach the design speed. Moreover, this is a two-stroke diesel engine, which consumes a lot of fuel. We are going to build a cruise ship. If the fuel consumption is too high, customers will not be able to accept it."
"The MTU V16 396 TE74L power diesel engine I plan to use can output 6,800 horses each, which is 40% larger than the domestic engine. Only in this way can the design speed be reached. What you are most interested in is the high speed I am talking about.
, if you can’t achieve it during the sea trial, you should pass the blame to me again.”
Qin Tao looked at the two people in front of him: "This is currently the most commonly used marine diesel engine in the world. Although we have to import it now, it will definitely be made domestically in the future. By then, there will be no need to modify the design. Isn't this killing two birds with one stone?"
We can’t be afraid of spending money now.”
PS: MTU represents the manufacturer of the diesel engine, 16 represents 16 cylinders, V represents the cylinder layout is V-shaped 90 degrees, 396 represents a single cylinder displacement of 3.96 liters, T represents turbocharging, and E represents the use of fresh water to cool the charge air.
, that is, supercharged and intercooled, 4 represents the design index, and L represents improved. The East China Hero wasted a lot of effort to find the model of the engine of this speedboat, and I don’t know if it is correct.