Alcoa’s new temper for marine sheet aluminium is specifically designed to provide both commercial and naval shipbuilders with improved corrosion resistance.
An addition to the established Nautic-AL family of marine sheet products, H128 meets an accelerated corrosion test specified by the U.S. Navy to provide resistance to sensitisation and contribute to ships meeting and exceeding their planned service life.
The excellent corrosion resistance of Nautic-AL alloys is one of their most important characteristics, Alcoa says. Welds of these products are as corrosion resistant as the parent alloy. Under certain conditions, however, such as exposure to high temperatures, marine alloys may become susceptible to inter-granular and exfoliation corrosion.
Regular, prolonged, periods of deck temperatures above 70 degrees Celsius have been recorded on Naval ships and corrosion, in combination with the stress endured during the long service life of a vessel, can lead to cracks in both painted and unpainted ship hulls. This inevitably leads to higher maintenance costs or substantial repair costs to remedy water intrusion.
Nautic-AL H128 provides superior thermal stability and higher corrosion resistance, reducing risk and lowering maintenance and repair costs, Alcoa says. Additionally, the company adds, building with H128 offers the possibility of cost saving through less painting costs and simplified warranty plans.
“With its improved thermal stability and corrosion resistance, Nautic-Al H128 will set a new standard in civil shipbuilding”, says Bernd Schäfer, Alcoa commercial vice president, global commercial transportation and industrial products, in a company news release. “With this innovation, Alcoa underlines its continued commitment to the civil marine sector to provide value-adding products for the benefit of our business partners.”
Alcoa is the first manufacturer to register this new temper, developed through a two-year collaboration programme between Alcoa’s technical and manufacturing facilities in Fusina (Italy) and Davenport (USA), the company says. Both plants are capable of producing the new temper in a wide range of thicknesses and widths.
The temper has been registered at the U.S. Aluminium Association, and successfully passed the ASTM B928/B928M ballots. It also received the marine certificate for civil shipbuilding from one of the leading global classification societies, Lloyds Register.
