TECH – China has achieved a critical breakthrough in materials science with the development of CHSN01—short for China High-Strength Low-Temperature Steel No. 1. This advanced alloy is specifically engineered to address one of the most demanding challenges in nuclear fusion reactor design: finding a material strong enough to withstand extreme magnetic fields, mechanical stress, and cryogenic temperatures—all at once.
First conceptualized in 2011, CHSN01 emerged from concerns among Chinese scientists that existing materials, such as the widely used 316LN stainless steel (adopted by international fusion projects like ITER in France), would eventually reach their performance limits. While some foreign experts considered 316LN sufficient for fusion applications, Chinese researchers took a different view—anticipating future stress loads and environmental extremes that would require stronger, more adaptable alloys.
Under the guidance of renowned cryogenic physicist Zhao Zhongxian, development of CHSN01 accelerated. By August 2023, the material had met and even exceeded national performance standards: a minimum yield strength of 1,500 MPa, over 25% elongation at cryogenic temperatures, and the ability to withstand mechanical stress up to 1,300 MPa and magnetic fields as strong as 20 Tesla. These properties far surpass the requirements for ITER and represent a major step forward in the quest for viable fusion energy.
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Currently, CHSN01 is being deployed in China’s own fusion project, known as BEST (a compact experimental reactor initiative launched in 2023 and expected to be completed by 2027). Of the 6,000 tonnes of components planned for the reactor, approximately 500 tonnes are CHSN01-based chilled conductor jackets—providing critical durability and insulation in fusion core components.
But CHSN01’s utility goes beyond fusion. Its combination of cryogenic ductility, magnetic resistance, and industrial scalability makes it highly valuable for other high-tech sectors, including superconducting magnets, cryogenic facilities, and high-field physics labs.
By successfully developing this steel, China has not only solved a key technical challenge for fusion energy, but also reinforced its leadership in next-generation materials engineering. CHSN01 stands as a strategic milestone in Beijing’s plan to achieve commercial fusion power by 2050, demonstrating how a coordinated national effort—linking research institutes, material manufacturers, and welding experts—can drive innovation with global impact.
