H. Sano, K. Kato, Sumitomo Light Metal Industries, LTD., Nagoya, Japan; K. Kamimuki, E. Noguchi, Kawasaki Heavy Industries, LTD., Kakamigahara, Japan

Summary:

2024 has high static strength and fatigue strength, and has been applied to the primary structures of aircrafts for nearly a half-century. It has disadvantages of corrosion resistance and formability. Alcoa developed 6013 as the alternative alloy for 2024, but 6013-T6511 has 20% lower strength than 2024-T3511. We have succeeded in the development of a new improved alternative alloy, 2013, from 6013. This 2013 can be extruded to thin complex shapes. 2013-T6511 extrusion has higher strength and much higher corrosion-resistance than 2024-T3511. Therefore, 2013 can reduce assembly cost by means of integrated structure and maintenance cost by longer intervals for re-coating. From this perspective, 2013-T6511 extrusion can be the only alternative alloy for 2024-T3511. This alloy has been registered as 2013 to The Aluminum Association in 2003. AMS of SAE published the specification for aircraft material as AMS4326. In order to approve this strict specification, the preparation for registration in Metallic Material Properties Development and Standardization, which has been changed from MIL HDBK, is in progress.