Giant ships also have Iron Man's "armor"? The "secret weapon" in shipbuilding

Did you know that behind those giant ships that transport liquefied natural gas (LNG) is a magical material called Invar. Just like Iron Man's armor, Invar has extraordinary capabilities and ensures the safe navigation of LNG ships.

About Invar Steel

Invar steel is a nickel-steel alloy, the main components of which are iron and nickel, with a nickel content of about 36%. Unlike ordinary steel, the biggest feature of Invar steel is its extremely small coefficient of thermal expansion. This means that even if the temperature changes greatly, the size of Invar steel can remain almost constant.

This magical property comes from the addition of nickel. The electronic structure of nickel atoms is different from that of iron atoms, which makes the crystal structure of Invar steel more stable and its sensitivity to temperature changes is greatly reduced.

Invar Steel and LNG Ships

Liquefied natural gas (LNG) is a clean and efficient energy source. Its transportation and storage around the world cannot be separated from LNG ships. However, the transportation and storage of LNG have extremely high requirements for materials:

Low temperature environment: The storage temperature of LNG needs to be maintained at around -163°C, so the ship's tank materials must be able to withstand extremely low temperatures.

Dimensional stability: In low temperature environments, the dimensions of the tank must remain stable to prevent deformation and leakage caused by thermal expansion and contraction.

Corrosion resistance: The tank material must withstand corrosion from seawater and air to ensure long-term safe use.

With its excellent performance, Invar steel perfectly meets the stringent material requirements of LNG ships. In the manufacture of LNG ships, Invar steel is mainly used to build the liquid cargo tank containment system, which is the core part of the liquefied natural gas. It can be said that Invar steel is the "secret weapon" in the manufacture of LNG ships, and has made important contributions to the safe transportation and storage of LNG.

Interesting story

The discovery of Invar steel was an accidental event. In 1896, Swiss physicist Charles Édouard Guillaume accidentally discovered a strange phenomenon while studying nickel-steel alloys: this alloy hardly expanded or contracted due to temperature changes when it was close to room temperature. This discovery surprised Guillaume so much that he named the material "Invar", which means "unchanged". He won the Nobel Prize in Physics in 1920 in recognition of his contribution to the precision measurement of physics by discovering the abnormal phenomenon in nickel-steel alloys.

my country's major achievements in the field of Invar steel

After years of hard work, China has successfully developed Invar steel and achieved industrial trial production of this special material in a short period of time, breaking France's long-standing monopoly on Invar steel production technology. Invar steel developed by China can maintain stable performance under ultra-low temperature conditions of -196 degrees Celsius, meeting the needs of high-end manufacturing fields such as LNG carriers.

Invar steel is known as one of the most difficult materials to weld in history due to its extremely low thermal expansion coefficient and extremely high requirements for welding technology. my country has trained professionals who master the welding technology of Invar steel. Although such talents were very scarce at first, with the passage of time and the spread of technology, welding technology has gradually improved, providing key technical support for China's shipbuilding industry, especially the construction of LNG carriers.

Future Outlook

With the advancement of science and technology, the application fields of Invar steel will continue to expand. For example, in the fields of aerospace, nuclear industry, etc., Invar steel also shows great application potential. I believe that in the future, Invar steel will bring more surprises and miracles to mankind.

Source: Chongqing Radio Science Popularization Experience Center

Audit expert: Zhang Qiyi

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