EH40 super-thick marine steel resistant to corrosion of tropical marine climate and manufacturing method thereof

By adding specific microalloying elements to EH40 grade marine steel and using a high-purity metallurgical process to optimize the microstructure, the corrosion problem of EH40 steel in tropical marine environments has been solved, resulting in extra-thick marine steel plates with high strength, high toughness, and excellent weldability.

CN120843947BActive Publication Date: 2026-01-09ANGANG STEEL CO LTD
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Patent Information

Application Number
CN202511349981.5
Authority / Receiving Office
CN · China
Patent Type
Patents(China)
Current Assignee / Owner
Filing Date
2025-09-22
Publication Date
2026-01-09
Estimated Expiration
2045-09-22

AI Technical Summary

Technical Problem

When EH40 grade marine steel is used in tropical marine environments, the existing rust layer is loose and porous, with poor protection, high corrosion rate, and easy to cause early corrosion and local perforation failure. In addition, the uneven structure of extra-thick steel plates affects the strength, toughness and corrosion resistance.

Method used

By incorporating microalloying elements such as C, Mn, Ni, Cu, Co, Sn, V, and Ti, and combining high-purity alloying smelting, heavy casting pressure, electroslag remelting, two-stage low-temperature controlled rolling, and tempering processes, the chemical composition and microstructure are optimized to improve the corrosion resistance and mechanical properties of the steel plate.

Benefits of technology

It significantly improves the corrosion resistance of EH40 extra-thick marine steel in tropical marine climates, with a yield strength ≥420MPa, tensile strength 600~680MPa, transverse elongation ≥26%, Charpy impact energy of the steel plate core at 20℃ ≥200J, seawater corrosion rate is less than 40% of that of conventional steel, and marine atmospheric corrosion rate is less than 50%.

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Abstract

The present application relates to the technical field of super-thick marine steel resistant to corrosion in tropical marine climate, in particular to an EH40 super-thick marine steel resistant to corrosion in tropical marine climate and a manufacturing method thereof. The steel is composed of the following chemical components by weight percentage: C: 0.065%-0.08%, Si: 0.15%-0.3%, Mn: 1.5%-1.7%, P≤0.02%, S≤0.01%, Als: 0.015%-0.03%, Ni: 0.4%-0.8%, Cu: 0.1%-0.2%, Co: 0.1%-0.15%, Sn: 0.05%-0.15%, V: 0.01%-0.03%, Ti: 0.01%-0.015%, N: 0.002%-0.004%, and the rest is Fe and inevitable impurities. The thickness of the finished steel plate can reach 100 mm, while maintaining the high strength, high toughness and excellent weldability of the EH40 grade, the corrosion resistance of the steel in the tropical marine climate environment is significantly improved.
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