marine steel is a special steel specially used for manufacturing ship hull structures. Its performance directly affects the safety and service life of ships. This type of steel needs to have high strength, corrosion resistance, low temperature resistance and good welding performance to cope with complex marine environments.
1. Classification system of marine steel
Marine steel can be divided into two categories according to strength grade: general strength steel and high strength steel. General strength steel includes four grades: A, B, D, and E. Their yield strength is 235MPa, but the impact toughness increases with the decrease of temperature. For example, E-grade steel can maintain stable performance at -40℃. High-strength steel is represented by AH32, DH36, etc., with yield strength ranging from 315MPa to 390MPa. By adding alloy elements and controlled rolling process, the mechanical properties of the material are significantly improved.
2. Special performance requirements
1. Corrosion resistance: Salt spray and microbial erosion in the marine environment require the formation of a dense oxide film on the surface of the steel. By adding elements such as chromium and molybdenum, or using coating technology, electrochemical corrosion can be effectively resisted.
2. Low-temperature toughness: Special scenarios such as the Arctic route require steel to remain ductile at - 60°C, and F-grade steel is designed for such requirements.
3. Welding processability: The complex structure of the hull requires steel to have good welding adaptability, and the carbon equivalent is strictly controlled to avoid cracks in the heat-affected zone.
3. Typical application scenarios
1. Civilian ships: The main structures of cargo ships and cruise ships mostly use high-strength steels such as AH36 and DH36, and their maximum thickness of 220mm can withstand the impact of huge waves.
2. Military ships: 945 steel (10MnNiCr) is the main material for domestic warships. Its yield strength reaches 450MPa. It has both seawater corrosion resistance and explosion resistance, and is suitable for surface ships such as destroyers and frigates.
3. Marine engineering: Offshore drilling platforms use ultra-high-strength steels such as EH36, which can withstand deep-sea high pressure and extreme temperature changes.
4. Technological development trends
With the development of large-scale and intelligent ships, marine steel is upgrading towards high toughness and light weight. For example, new materials such as 980 steel use nano-precipitation strengthening technology to reduce dead weight while maintaining high strength. In addition, the corrosion prediction system assisted by artificial intelligence is gradually realizing the healthy management of steel throughout its life cycle.
The technological progress of marine steel not only promotes the innovation of the shipping industry, but also carries the important mission of the strategy of building a strong maritime nation. In the future, with the continuous breakthroughs in materials science and manufacturing processes, marine steel will show more possibilities in the fields of greening and intelligence.
