Abstract
Al-Li alloys form a new generation of aluminium alloys with unique construction parameters, namely, high static and dynamic strength, low density, high Young’s modulus and satisfactory weldability. However resistance to stress corrosion cracking (SCC) and exfoliation corrosion in various corrosion aggressive environments are not completely understood. The purpose of the present work is to determine the resistance to SCC and to estimate exfoliation corrosion of the Al-Li alloys semiproducts in various environments. Samples were tested in different climate conditions: Barents Sea coast, Cuba island coast, Moscow industrial zone, sea tropics environment on board of the "Izumrud" vessel. In addition, laboratory corrosion studies have been carried out and electrochemical characteristics of industrial and experimental alloys have been determined. Sea tropics of the corrosion station on the Cuba island and of the Indian Ocean (specimens testing on board of the scientific vessel "Izumrud") are established to be the most aggressive corrosion environments, and the threshold stress for stress corrosion cracking equals 150 MPa. The least aggressive corrosion environments are Moscow industrial zone and Barents littoral sea - the threshold level of stresses at stress corrosion cracking equals 250 MPa. Laboratory tests for stress corrosion cracking resistance well correlates the results obtained in the sea tropics environment. During corrosion cracking cracks predominantly have inter- crystalline crack propagation. But the fracture in the mechanical break zone significantly differs from traditional 2xxx and 7xxx series alloys. The fracture behavior of propagation the crack in this zone changes to trans-crystalline. Al-Li alloys have a good exfoliation corrosion resistance level in all the environments.
