22nd Congress of International Council of the Aeronautical Sciences, Harrogate, UK, 28 August - 1st September, 2000
Paper ICAS 2000-4.4.3

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

A. Lanciotti (1), L. Lazzeri (1), S. Ottaviano (2)
(1) University of Pisa, Italy; (2) Alenia Aerospazio, Italy

Keywords: titanium welding, fatigue crack growth, isopropyl alcohol, scc

The paper presents the main results of a collaboration between the Department of Aerospace Engineering of the University of Pisa and Alenia Aerospace, for the evaluation of damage tolerance and fatigue behaviour of TIG welded Ti-6Al-4V sheets. Particular care was paid to the assessment of corrosive environment effects, since the most significant applications are in space vehicle tanks. Residual stresses were also evaluated, in order to analyse more appropriately the results of all the tests. Resistance of welded panels to fatigue crack growth is comparable to the one of the base metal, being penalised only for cracks growing orthogonally to the weld bead, that are influenced by the residual stresses field. The environment has a significant effect on fatigue crack growth, but the resistance to stress corrosion cracking is very good. Durability characteristics of welded butt joints are also good. No particular environment effect is appreciated on durability.

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