A steel-clad vision for naval innovation

At the 2025 Maritime Defense Industry Exhibition (MADEX) in Busan, two of South Korea’s industrial giants, POSCO and HD Hyundai Heavy Industries, announced a landmark collaboration to reshape the future of naval warfare. The memorandum of understanding, signed on May 28, outlines their commitment to developing and deploying POSCO’s proprietary high-manganese steel as a core material in next-generation warship hulls. This partnership is set to position South Korea at the forefront of advanced marine defence manufacturing.

Unlocking the Potential of High-Manganese Steel

The central innovation lies in POSCO’s high-manganese steel, a material globally pioneered by the company and previously used in liquefied natural gas containment systems. This steel is non-magnetic, a critical characteristic for military vessels that must evade detection by magnetic influence sea mines. It also offers approximately 10% greater tensile strength than standard shipbuilding steel, dramatically increasing a vessel’s resistance to external shocks such as underwater blasts or missile impacts. In addition, its mechanical properties allow for hull thickness reduction, decreasing overall vessel weight while maintaining durability.

Strategic Synergy Between Steelmaker & Shipbuilder

HD Hyundai, the world’s largest shipbuilder, will apply its extensive expertise in naval engineering and production to integrate high-manganese steel into future military platforms. Together, the two companies will conduct joint research and testing to validate the material’s performance in ship-scale conditions, including stress fatigue, welding compatibility, and corrosion resistance in marine environments. This will involve simulation modelling and eventual pilot vessel construction to demonstrate real-world feasibility.

The goal is to move beyond experimental use into full industrial deployment, with applications ranging from coastal defence vessels and destroyers to unmanned naval systems and special-purpose ships.

From material innovation to maritime strategy

The strategic implications of this partnership extend beyond metallurgy. Traditional naval vessels require complex demagnetisation processes, also known as degaussing, to reduce vulnerability to magnetically triggered explosives. High-manganese steel bypasses this need entirely, enhancing operational safety and reducing maintenance costs and logistical complexity. For navies, this means faster deployment, increased stealth, and improved survivability under threat.

This innovation aligns with South Korea’s broader defence posture, which increasingly relies on indigenously produced platforms and technologies to maintain regional security and reduce reliance on foreign supply chains.

MADEX 2025: A Platform for Defence Innovation       

The announcement was made at MADEX 2025, South Korea’s premier naval and defence exhibition, held at BEXCO in Busan. The event featured participation from the Republic of Korea Navy, the Defense Acquisition Program Administration, global defence contractors, and shipbuilding experts.

During the event, POSCO presented two technical white papers: “Current Status of New Material Development for Improving Naval Vessel Survivability” and “Non-magnetic High-manganese Steel as Hull Material for Special Purpose Vessels.” These papers underscored the steelmaker’s commitment to pushing the boundaries of naval metallurgy and substantiated the performance data of their new material in both lab and marine conditions.

Reinforcing Domestic Defence Autonomy

This partnership is expected to significantly contribute to South Korea’s goal of strengthening its domestic defence manufacturing capabilities. By using Korean-developed steel in high-value military projects, the collaboration boosts local content, supports skilled employment, and reduces dependency on imported materials.

POSCO also plans to package its high-manganese steel with a wider portfolio of specialised defence-grade steels, tailored for military shipbuilding. The initiative will help standardise a new material ecosystem for the Korean Navy and defence contractors, potentially becoming a reference point for export-oriented defence contracts.

Preparing for Global Maritime Competitiveness

Both firms also see a global opportunity in marine defence exports. With naval budgets rising in Southeast Asia, the Middle East, and Europe, next-generation vessels with enhanced survivability and lower detection profiles are in demand. By proving the efficiency and reliability of high-manganese steel in Korean-built naval vessels, POSCO and HD Hyundai could offer strategic solutions to allied nations seeking advanced but cost-effective defence capabilities.

The technology could also serve dual-use applications, such as high-speed civilian patrol boats, research vessels in polar regions, or security ships in piracy-affected waters, all environments where weight, durability, and low detectability are key.

Industry Voices Underline Long-Term Vision

A senior POSCO official stated, “Based on our world-class steelmaking technology and decades of innovation, we are proud to lead the development of advanced non-magnetic materials like high-manganese steel. This partnership will not only improve survivability of future warships but will serve as a foundation for broader national defence revitalisation.”

HD Hyundai executives also voiced strong support, describing the MOU as a “critical first step” in transforming warship construction through advanced materials and showcasing Korean leadership in naval engineering to the world.

Key Takeaways:

• POSCO and HD Hyundai signed an MOU at MADEX 2025 to co-develop high-manganese steel applications for naval vessels, improving stealth and survivability.

• High-manganese steel is non-magnetic and 10% stronger than traditional ship steel, offering protection against sea mines and reducing hull weight.

• The collaboration supports South Korea’s defence autonomy and positions both firms for global marine defence export opportunities.