Stress Corrosion Resistance of Damage Tolerant Aluminium-Lithium Sheet Materials

摘要

The Stress Corrosion Cracking (SCC) resistances of three damage tolerant aluminumsheet materials were determined by means of the ASCOR (Automated Stress COrrosion Ring) test. The conventional damage tolerant sheet material 2024-T3 was used as reference. The SCC resistance of 8090-T81 turned out to be only slightly lower than the SCC resistance of 2024-T3. In contrast, 2091-T8X exhibited a much lower SCC resistance. However, the so-called CPHK treatment brought the SCC resistance of 2091-T8X to the level of 2024-T3 and 8090-T81. The favorable effect of the CPHK treatment is, at least partly, explained by the grain structure: the pancake grain structure of 2091-T8X-CPHK (as compared with the equiaxed grain structure of 2091-T8X) hinders SC crack growth. Other microstructural differences between 2091-T8X and 2091-T8X-CPHK were not found. The subject of grain boundary segregation was not touched upon, however, and deserves attention.