Effect of aging treatment on the exfoliation corrosion and stress corrosion cracking behaviors of 2195 Al–Li alloy

Abstract

2195 Al–Li alloy was processed by solid solution heat treatment and then aged at different temperatures, and its microstructure, mechanical properties, inter-granular corrosion (IGC), exfoliation corrosion (EXCO) and stress corrosion cracking (SCC) behaviors were observed and determined by scanning electron microscopy (SEM), transmission electron microscopy (TEM), immersion test in IGC and EXCO solutions, electrochemical impedance spectroscopy (EIS) and slow strain rate tensile (SSRT) test. The results reveal that the size and density of T1 precipitates at grain boundary are increased with increasing aging temperature whereas the density of T1 phases in grain is increased firstly and then reduced slightly. The IGC and EXCO susceptibility of 2195 alloy is increased while its SCC susceptibility in 3.5% NaCl solution is low and hardly influenced by the aging temperature. The hardness and tensile strength are increased at first and then decreased, but the elongation and static toughness values are declined with aging temperature. The optimum heat treatment for the practical application of 2195 alloy is the aged at 155°C for 14h temper.