China achieves mass production of rocket propellant tank domes using cryogenic forming technology

A Chinese research team has successfully mass-produced rocket propellant tank domes using their pioneering cryogenic forming technology, which can reduce production cycle time by more than 90 percent.

The team, from the lab of high-performance precision manufacturing at Dalian University of Technology’s School of Mechanical Engineering, has developed the world’s first large cryogenic forming press to make one-piece rocket propellant tank domes over two meters in diameter from aluminum alloys.

In cooperation with a Chinese company, they have realized the production capacity of about 1,000 tank domes per year.

“The key to cryogenic forming is cooling large plates into the cryogenic zone. This equipment has broken through the challenges of rapid transport and precise temperature control of large-volume liquid nitrogen, as well as coordinated loading control of multiple parameters, including temperature, pressure, and displacement. It enables the control of liquid nitrogen at minus 190 degrees Celsius, the designed cooling of materials, and thus stable manufacturing of large components. It can reduce the production cycle time by 90 percent from more than one week to just a few hours,” said Fan Xiaobo, a researcher at the school.

The cryogenic forming press can make a rocket propellant tank dome out of a four-millimeter aluminum alloy plate in a single step, with a thickness deviation of less than 0.3 millimeters.

The core enabler of the stable operation of this equipment is the aluminum alloy cryogenic forming technology pioneered by the team.

“Generally, metals become brittle at cryogenic temperatures, so they are considered harmful. However, our research team discovered that aluminum alloys in a specific state not only avoid cold brittleness but also exhibit higher elongation and hardening indexes at cryogenic temperatures. Using this abnormal phenomenon, we have developed the world’s first aluminum alloy cryogenic forming technology, and transformed the conventional approach of ‘heating when ambient temperature fails’ to a cryogenic approach, enabling us to make a monolithic tank dome from a thin plate in one go. The forming press can generate a finished product that can be used directly, requiring no further welding or milling,” Fan said.

The new tank domes have been successfully applied in flight missions of Long March-12 and Long March-7A Y14 carrier rockets.

“This technology enables the production of one-piece tank domes, which is especially critical for reusable rockets. We will continue to push forward and apply this cryogenic forming technology to enable self-reliance in aircraft and unmanned systems and to promote low-cost manufacturing of thin-walled structures for new-energy vehicles and high-speed trains,” said Qi Chang, head of the school.

Lao officials accompanying President Thongloun Sisoulith on his visit to the eastern Chinese province of Zhejiang have expressed hope for more technological cooperation with China and a desire to learn more from the country’s development experience.

Thongloun, also general secretary of the Lao People’s Revolutionary Party Central Committee, arrived in Zhejiang’s provincial capital Hangzhou on Tuesday to begin a five-day state visit to China.

Zhejiang was chosen as the first stop of the Lao President’s trip for its reputation as a high-tech and innovation hub and for having achieved high-quality growth across multiple sectors.

After arriving, Thongloun visited several local technology companies, where he explored advanced AI-powered robotic systems designed for industrial, commercial and challenging environments.

He observed the smart logistics and e-commerce systems of tech giant Alibaba, as well as the quadruped robots and embodied AI technologies of Deep Robotics, another Hangzhou-based firm.

The tour reflected Laos’ growing interest in AI, cloud computing and robotics.

“It’s very amazing, in terms of modern technology nowadays. We are at the beginning of this cooperation because based on the cooperation potential of the two countries, I think we can work together in this area,” said Bounleua Phandanouvong, head of the Lao People’s Revolutionary Party Central Committee’s Commission for External Relations.

On Wednesday, Thongloun traveled to the nearby Anji County in Huzhou City to examine local green initiatives, including a center promoting sustainable bamboo products and ecological conservation, serving as a vivid example of China’s rural revitalization initiatives.

Somphone Sichaleune, the Lao ambassador to China, highlighted the people-centered philosophy which is at the heart of the Communist Party of China (CPC)’s governance approach, and said the Lao officials are keen to learn from China’s development experience.

“The CPC is from the people, by the people, and for the people. That is really important. People-centered [philosophy] — that is very important. So Laos, as we develop our plan to the common goal of socialism, so we learned a lot of very useful, very important examples from China,” he said.