Development of new steel plates for shipbuilding

Posted:5/27/2011 11:19:47 AM

In recent years, more attention has been paid to the safety and durability of ships and environment protection of sea, which have led to the development of new structural steel plates. One of them is the development of more corrosion resistant plates for double-hull tankers. Crude oil carriers are now required to have double hulls to prevent oil spill, and an increase in temperature in oil tanks with the double hull structure increases the likelihood of corrosion of upper deck steel plates exposed to the vapor space in the tanks. To prevent the corrosion and to increase the lifetime of the ships, different corrosion
resistant steel plates have been developed
The development of new steel plates has also been made to increase construction efficiency and thereby to decrease construction cost. Longitudinally profiled (LP). Thickness change within a plate was achieved by controlled rolling, which made it possible to replace the plates which had been made by welding steel plates of different thickness,and therefore to reduce the welding time and cost
Another development is concerned with residual stress retaining in steel plates.TMCP steel plates are likely to possess residual stresses from their production, and this often results in distortion in different ways after cutting and welding of the plates. In order to achieve residual stress-reduced steel plates, temperature differences over the large surface area in a wide and long plate and through the thickness should be minimized and cold levering is also used for the purpose of reducing inhomogeneous stress for block shape accuracy.
A number of research projects are currently being carried out on European and national levels to improve the application of lasers and optical technologies in shipbuilding as shown in Fig. In laser beam welding, centre line solidification cracks in the fused zone are an issue and can limit the travel speed and, hence productivity. The fused zones are typically of the same composition as the steel being welded and whilst there are
several welding procedural factors which can be used to minimize the risk of cracking, the problem hinges on the steel composition. Lower S and P levels may thus be required
Most steelmakers are increasingly working with the joining community so that welding issues are being assessed early in the development program. In summary, although a lot of progress has been made over the last thirty years in steel plates and welding technology forshipbuilding, there are still growing demands from the view of energy transport, logistics, safety, environment and so on.