Study of pre-strain before artificial aging on mechanical property and stress corrosion behavior of 2297 Al–Cu–Li alloy

Abstract

The influence of pre-strain (2%, 5%, 8% and 12.5%) and aging state (under, peak and over aging) on mechanical properties and stress corrosion behavior of 2297 Al–Cu–Li alloy was studied. The peak microhardness of the alloy reaches 156.3 HV at 15 h with 12.5% pre-strain, and that of the alloy is only 115.6 HV at 31 h without pre-strain. The slow strain rate testing results indicate the low stress corrosion cracking factor for the samples without pre-strain and high stress corrosion cracking factor for the samples with pre-strain, and the stress corrosion cracking factor of the peak-aged sample with 12.5% pre-strain reaches to 33.3%. From the transmission electron microscopy characterization, it can be inferred that the quantity and distribution of T1 (Al2CuLi) precipitates significantly affect the stress corrosion behavior of 2297 Al–Cu–Li alloy. The over-aged sample exhibits poor stress corrosion resistance, resulting from the large numbers of coarse T1 precipitates and precipitation free zone at the grain boundary.