M. Nievergelt, M. Geering, M. Zgraggen, M. Harzenmoser

The use of large and complex integral parts in modem lightweight structures results in increased efforts if these parts need to be replaced. Therefore, to repair a damaged part is often more economical and faster to accomplish than to carry out a part replacement. In addition to well known repair methods, repair by welding may have a high economical potential in certain aerospace applications when technical feasibility can be demonstrated. Modern lightweight structures often embody parts made of titanium alloys to ensure the fatigue life requirements, e.g. the three carry-through bulkheads of the Swiss F/A-18C/D model. Ti-6Al-4V offers a good weldability and is often used in the annealed condition. Therefore, in service repairs by welding might be feasible. To perform an in situ weld-repair of structural parts using the tungsten inert gas (TIG) welding method without furnace heat treatment is questionable, and a poor fatigue performance is expected. However, as a weldrepair may be applied more than one time, a significant shorter fatigue life compared to the baseline life may still be acceptable. The studys focus was to determine the fatigue behavior (crack nucleation and crack growth life) of weld-repaired specimens compared to baseline specimens. In order to explain large variations of the fatigue behavior, the microstructure of the weld and the heat affected zone (HAZ) of selected specimens were metallographic analyzed and correlated to the welding parameters that were used. The average lives of the weld and the HAZ are in the range of 23% to 76%, compared to the average baseline lives. The results of the study indicate that the repair of structural titanium parts by welding might be an alternative for certain aerospace applications. However, in order to set up a qualified repair process, a large amount of further investigation needs to be done.

23rd ICAF Symposium of the international Committee on Aeronautical Fatique, 2005, Hamburg

Conference Poster

englisch

A5, 18 Seiten

DGLR-Bericht, 2005, 2005-03, 23rd ICAF Symposium of the international Committee on Aeronautical Fatique - Proceedings; S.551-568; 2005; Deutsche Gesellschaft für Luft- und Raumfahrt - Lilienthal-Oberth e.V., Bonn

NA

welding, repair, titanium

Bestellbar

2005