Micro-mechanisms of deformation accommodation in AA7050 alloy in the presence of hydrogen

Abstract

The interaction of hydrogen with dislocations in AA 7050 alloy heat treated to produce different matrix precipitates is studied using interrupted micro-tensile tests of pre-charged specimens and electron back scattered diffraction (EBSD). Hydrogen promoted slip planarity as well as sub-grain formation in the overaged condition having incoherent ƞ (MgZn2) precipitates, while it enhanced dislocation looping and pitting in case of higher density Mg-Zn precipitates (GP II) dominated alloy. For the first time, a semi-quantitative analysis on the extent of the effect of hydrogen on micro-mechanisms of deformation evolution is carried out using sufficient statistics through large area scans in EBSD. It is shown that the interaction of pre-charged hydrogen with the microstructure was unaffected by recrystallization as well as texture till 6% strain.