Aluminium alloys in shipbuilding – a fast growing trend

Trends in shipbuilding have become similar to those in the automobile industry in recent years and the growing demand for automobiles, heavy duty vehicles, aircrafts, trains and ships is also set to significantly spur demand for aluminium flat rolled and extruded products. In fact, the use of aviation, marine and rail transportation will likely increase to such an extent that their combined energy demand is expected to equal about 85 per cent of the amount used by light-duty vehicles by 2040, up from about 50 per cent in 2014, according to Exxon Mobile.

The necessity for lowering the weight of different ships, in order to increase the payload and reduce fuel consumption, has turned shipbuilders towards aluminium alloys due to their potential to reduce the weight of ship structures by up to 50 per cent, compared to those made from low carbon steels.

Additionally, the roughly five times higher costs of Al–alloys, with respect to the costs of low-carbon steel, become acceptable if taking into account the total cost increase on one hand, and the payload increase as well as the excellent corrosion resistance, on the other (lower maintenance costs). Al-alloys also directly reduce the loss of cargo dead weight due to the lighter structure of a ship while at the same time improving the ship’s stability. Moreover, by reducing the vessel’s weight, the use of aluminium alloys allows for higher speeds, greater payloads, lower fuel consumption, longer distances and excellent manoeuvrability.

The material costs of building a ship are only 1-2 per cent of the total cost of the ship. Major costs are associated with the manufacturing of the ship. Today’s advancements in manufacturing with aluminium alloys are offering significant cost saving factors, and making aluminium ships in parity with steel ships could be the future.

Shipbuilders such as Australian company Austal are implementing additional improvements in the production of aluminium ships – involving router cutting, work kitting, complex extrusions and welding – that will significantly improve productivity and reduce costs in the future, since labour is the highest cost when building a ship using aluminium alloys.

There is currently no available reliable data concerning how much aluminium alloys are used by shipbuilders in more than 430 shipyards around the world, but an approximate (author's personal view) estimate it is about 1 -1.2 million tonnes per year, most of which belongs to rolled aluminium products (75-80 per cent).