DURABILITY, DAMAGE TOLERANCE AND ENVIRONMENTALLY ASSISTED CRACK PROPAGATION CHARACTERISTICS OF A TIG WELDED TITANIUM ALLOY

摘要

The paper presents the main results of arncollaboration between the Department ofrnAerospace Engineering of the University of Pisarnand Alenia Aerospace, for the evaluation ofrndamage tolerance and fatigue behaviour of TIGrnwelded Ti-6Al-4V sheets. Particular care wasrnpaid to the assessment of corrosive environmentrneffects, since the most significant applicationsrnare in space vehicle tanks. Residual stressesrnwere also evaluated, in order to analyse morernappropriately the results of all the tests.rnResistance of welded panels to fatigue crackrngrowth is comparable to the one of the basernmetal, being penalised only for cracks growingrnorthogonally to the weld bead, that arerninfluenced by the residual stresses field. Thernenvironment has a significant effect on fatiguerncrack growth, but the resistance to stressrncorrosion cracking is very good. Durabilityrncharacteristics of welded butt joints are alsorngood. No particular environment effect isrnappreciated on durability.