China has successfully completed the world's first 537-day deep-sea material corrosion test at a depth of 10,000 meters, setting a new global benchmark for sustained in-situ deep-sea testing duration, China State Shipbuilding Corporation (CSSC) announced on Saturday.

The milestone marks a critical breakthrough for China's deep-sea in-situ testing technology, transitioning from comprehensive depth coverage to full-cycle capability mastery.

In-situ testing under extreme conditions

Unlike laboratory simulations, in-situ testing in the deep sea involves deploying scientific instruments directly into the natural deep-sea environment without retrieving samples to the surface, thereby preserving the original physicochemical conditions and yielding the most authentic data possible. 

The 537-day campaign was designed specifically to evaluate the corrosion resistance of various materials and coatings under prolonged exposure to ultra-deep-sea conditions.

Test materials and findings

The recovered specimens provide globally scarce empirical data on material behavior in real 10,000-meter deep-sea environments over extended periods.

"The test materials that spent 537 days at 10,000 meters show marked differences across coating systems – some remain intact while others exhibit significant corrosion," said Li Ning, a CMG reporter on site examining the retrieved samples.

Liao Zhiqian, deputy director of the CSSC 725 Research Institute, explained that the in-situ corrosion test framework carried a diverse array of specimen types, including ferrous and non-ferrous metals from the metallic category, functional coatings, sacrificial anode materials and non-metallic buoyancy materials.

Engineering impact

Liao said the recovered environmental data will improve understanding of long-term material behavior in real deep-sea conditions, support more precise corrosion-resistant design and enhance lifecycle prediction for subsea infrastructure.

The mission also led to the development of several new coating formulations for corrosion protection in deep-sea oil extraction and mining equipment.

Simulation infrastructure upgrade

The CSSC 725 Research Institute also used data from the 537-day mission to refine its self-developed deep-sea simulation system.

The system replicates extreme deep-sea conditions through high-pressure autoclaves and real-time environmental controls. It can correlate laboratory results with real deep-sea exposure data to improve simulation accuracy and support future engineering applications.

The 537-day test represents a pivotal advancement supporting China's strategic initiatives in deep-sea exploration, deep-sea mining and deep-sea oil and gas development.