On July 1, the world's first underwater welding in-situ neutron diffraction research device, independently developed by China, was put into operation on the engineering materials spectrometer of the China Spallation Neutron Source, and successfully completed the first in-situ observation experiment of the underwater welding process. This marks a major breakthrough in real-time observation of microstructure and revelation of core welding mechanisms during underwater welding, providing scientific support for the autonomous control of underwater welding technology for large underwater structures and the improvement of welding quality.
Underwater welding is one of the key core technologies for in-situ manufacturing and maintenance of large underwater structures such as nuclear power, offshore wind power, ships, and oil and gas pipelines, and is the main method for emergency and permanent repair of underwater structures.
In the past, underwater welding mainly relied on the "post-weld sampling" method, i.e., completing the welding underwater, then cutting samples and returning them to the laboratory for testing. The team innovatively proposed the development of an underwater welding in-situ neutron diffraction research device. This device aims to construct a "super underwater magnifying glass" with strong penetration capability in a laboratory environment, enabling in-situ observation of the underwater welding process by simulating the real marine underwater environment. In-situ observation means real-time monitoring of the dynamic changes in material microstructure during the welding process. Based on this, a closed-loop system is established to deduce process parameters from weld performance requirements.
After more than three years of research, the team has successively overcome core technical challenges such as underwater welding manufacturing under extreme conditions and the coordinated synergy between the in-situ welding device and large-scale spectrometers, constructing the world's first in-situ research device for underwater welding.