Now the LPG storage tanks for power ships all use this kind of Invar steel, and the production and processing of this metal material is so difficult that it was once monopolized by France for more than 50 years, and even the United States could not build it. China broke through the monopoly and realized independent production in just four years.
The strength and hardness of Yinwa steel is not high, and the texture of this alloy steel is very light and thin, which can be like paper, with a thickness of only 0.7 mm, less than 1 mm, but it has great plasticity and toughness, and can be used as sealing materials for electronic components, LPG storage materials for power carriers, and special transmission cables.
Yinwa steel can prevent the structure of the hull from freezing and cracking at low temperature, and avoid the general metal frost cracking at low temperature, but although Yinwa steel has excellent stability, it also has particularity. If you accidentally touch the steel surface with your fingers, the invisible sweat stains will rust it in 24 hours.
This characteristic makes the welding requirements of Yinwa steel extremely stringent, and it has become one of the most difficult alloy steels to process.
When welding Yinwa steel, workers need to wear special sheepskin gloves, there must not be any omission of solder joint, nor can sweat drop any drop on Yinwa steel, otherwise, when the huge tank for storing liquefied gas is completed, there will be a hidden danger from this pinhole-like leak, which will lead to the failure of the whole welding work and serious safety accidents, and the loss will outweigh the gain.
As a special raw material that must be used by large power ships, Yinwagang can safely store natural gas at a constant temperature of more than 100 degrees below zero, and keep the pressure constant, because liquid natural gas is dangerous. You can't change air into the tank, otherwise even a big spark with a needle tip may lead to LPG explosion in the whole cargo hold. Tens of thousands of tons of LPG once there is a safety accident. The consequences are incalculable.
If this technical requirement can not be met, it will be impossible to store and transport liquid natural gas, so the emergence of Yinwa Steel provides a great advantage for the development of power ships.
French GTT company has always had the technology and ability to produce Invar steel, and has been selling this special alloy steel to the world as an export enterprise. in order to develop China's shipbuilding industry and realize our independent production of special raw materials, our country also began to independently research and develop the production technology of Invar steel. After 4 years, we finally broke through many difficult problems and achieved the success of this technology.
The interior of the cargo tank of the LNG ship needs to be built with Invar steel. Now, with the continuous progress of technology, the production specification of Invar steel has increased from the initial 0.7mm to 1mm and 1.5mm, a total of three products.
The main difficulty in the production of this kind of Yinwa steel is that it is too thin, and complicated procedures are needed in production, which can only be completed through many processes, such as electric arc furnace forging, vacuum induction melting, oxygen decarburization, cold rolling and hot rolling, and so on. And there can be no omissions in any link in the processing process, even if a parameter is unqualified, it will cause the production of Yinwa steel to be unqualified.
Compared with the price of ordinary steel, the price of Invar steel is 20 times that of ordinary steel, and it has to be sold by kilograms. the cost of one kilogram is more than 100 yuan. 450 tons of Invar steel is generally needed to build a power ship. the cost of this project alone is nearly 50 million yuan.
Now, with the gradual increase in the scale of power ships, the demand for Yinwa Steel is also increasing. China's Yinwa Steel production enterprises are mainly Baoshan Iron and Steel Company, referred to as Baosteel, applying new technology, advanced talents, new materials and patented processing technology. can steadily produce Invar steel products, and participate in international exports, accept international orders and business cooperation, accelerate the development of China's shipbuilding industry and foreign trade economy. Laid a good foundation.
After solving the production problem, China has also made gratifying achievements in the processing technology of Yinwa Steel. Now many skilled workers have been trained to obtain the certification of internationally recognized senior skilled workers in the welding of Yinwa Steel. Specializing in the welding of Yinwa Steel in shipping enterprises, the Yinwa Steel is spliced together to achieve a real high-tech means to build liquefied tanks and use ultra-low temperature for storage and transportation.
Just because the construction technology is very complex and the cost is relatively high, many countries are prohibitive to the research and development of Invar steel. Although South Korea's shipbuilding industry is very developed, because it can not produce Invar steel raw materials, the Invar steel used is also developed by the French GTT company. Every power ship in South Korea is completed, using the maintenance system made by Invar steel, it has to pay tens of millions of dollars in patent fees to France.