Stronger steel for super-sized ships

(MHI) and

have jointly developed a technology to use higher tensile strength steel (HTSS) for super-sized containerships. The steel will be used to make the longitudinal strength member, an essential part of a container ship's hull.

As containerships increase in size to improve efficiency, the steel plates used for larger ships are becoming thicker, but this tends to decrease their toughness. HTSS offers toughness in addition to increased strength and reduced thickness and can contribute to improvements in weight reduction and fuel efficiency, while increasing the reliability of the ship's hull.

The containership will be built at MHI's Nagasaki Shipyard and Machinery Works while the HTSS steel plate will be produced at Nippon Steel's Oita Works.

The 47 kgf/mm² HTSS is the world's highest strength steel plate for the hull of commercial ships. Currently, the highest strength steel plate being used for commercial ships is 40 kgf/mm² HTSS, introduced fifteen years ago.

Nippon Steel developed the new HTSS by applying its Thermo-Mechanical Control Process (TMCP) technology, a production process that concurrently enhances strength, toughness and weldability of steel through hot rolling and online water-cooling. The company verified the safety of the steel through evaluation at a test facility with a tensile capacity of 8,000 tonnes.