Steel Products for Shipbuilding

Posted:5/27/2011 11:16:58 AM

Product designs and properties of steel products for shipbuilding are described. They are new TMCP (thermo-mechanical control process) steel plates, weldable with high heat input, for container ships and LP (longitudinal profile) plates, both contribute to the increase in productivity at shipyards through the large reduction of welding time, anti-corrosion steel plates for crude oil tankers NAC5 which contribute to high performance of ships from the viewpoint of corrosion, cladded steel plates for chemical tankers, anti-corrosion pipes, used in crude oil tankers for loading and unloading crude oil,  and shapes for shipbuilding which are produced using TMCP to realize weldability as good as steel plates.
In recent years, the shipbuilding industry has energetically promoted high performance of ships and improved productivity in construction in response to vessel diversification (trend toward exclusive-use ships). In the process, the industry has also pointed out a variety of developmental needs related to steel products, resulting in the creation of new technologies and new products.
In the field of plate, they include new TMCP (thermo-mechanical control process) steel plates for high heat input welding for container ships, which contribute to improved productivity by greatly reducing welding working time, and LP steel plates (longitudinally profiled plates, also called taper plates), new anti-corrosion steel plates for crude oil tankers, NAC5, which contribute to higher performance in ships through improved corrosion resistance, and clad steel plates for chemical tankers. Tubular products include crude oil tankers, which improves corrosion wear performance in onboard oil receiving pipes used in loading and unloading crude oil. Among shape steels, our Steel has developed TMCP technologies for shapes for shipbuilding which provide
weldability equal to that of plates.
With the increase in long distance freight transportation in recent year, the size of container ship has been enlarged rapidly, and even 8 000 TEU (TEU: twentyfeet equivalent unit) class container ships are being constructed recently. To construct such large-scale container ships, high strength and thick steel plates are used, such as 390 N/mm2 class yield strength and maximum thichness of 65 mm or more. For welding of these thick plates, 1-pass vertical electro gas arc weldingwhich has high welding efficiency, has been applied, and the heat inputs in these welding reach ultra-high level exceeding 400 kJ/cm. This high heat inputs cause the remarkable coarsening of microstructure in heat affected zone (HAZ), and greatly decrease the toughness of welded joint. Furthermore, in order to meet the requirements of higher strength and increased thickness, it is necessary to increase the carbon equivalent (Ceq) and/or to add alloying elements, but this causes deterioration in weldability and the toughness of welded joint
In response to the requirements of the shipbuilding industry, BEBON Steel has developed and commercialized advanced products such as water cooled TMCP steels which have now become world-standard products. In the future, BEBON Steel Group will continue to develop Only 1 and No. 1 products which meet the needs of the shipbuilding industry, for example, by contributing to higher productivity and higher performance, including ship collision safety, corrosion resistance, and fatigue resistance. Through the products mentioned above, BEBON Steel will contribute to the development of society and protection of the global environment.