Problems and prospect of Al-Mg alloys application in marine constructions

The position of steel as the most widely used material in the shipbuilding industry originates from the superior mechanical properties and low manufacturing costs The increasing demands for lowering the weight of different ships due to the increase of their sizes or generally increasing the payload, the application of Al - alloys offered the potential to lower the weight of structures by over 50% in comparison with those made of low-carbon steel. The roughly five times higher costs of Al - alloys production in respect to the costs of low-carbon steel become acceptable in a certain relations between the total cost increase on one hand, and payload increase as well as the excellent corrosion resistance, on the other hand. The evolution of ship performances promoted the need for the development of new Al - alloys with improved mechanical properties, corrosion resistance weldability, etc. In this paper the current efforts in alloys modifications for improving their marine service ability were considered, and assessment was made on the potential of the different aluminum alloy types for marine applications. The non-heat-treatable Al-Mg alloys were appointed as favorable ones in respect to the costs and all the required properties for successful vessel service. The paper deals with the current problems appeared in the aluminum marine service and with the metallurgical aspects of structure and property control which is necessary to ensure the successful applications.