GRAIN BOUNDARY SEGREGATION AND HYDROGEN-INDUCED FRACTURE IN 7050 ALUMINIUM ALLOY

摘要

The relationships between grain boundary segregation and crack growth of stress corrosion and corrosion fatigue in 7050 aluminium alloy have been investigated under various aging conditions; the effects of grain boundary segregation on intergranular fracture work have been calculated using a quasichemical approach. The results show that the hydrogen content at the crack tip and the crack growth rate increase with the concentration of solid solution Mg on increasing grain boundary; both Mg and H segregation induce the intergranular fracture work to decrease. Mg segregation accelerates H enriching and crack propagation. It is indicated that a Mg-H interaction occurs in the processes of corrosion fatigue as well as stress corrosion.