Failure analysis of titanium alloy (Ti6Al4V) fastener used in aerospace application

Titanium alloy fasteners are being used in space programme. These fasteners are coated with MoS 2, which serves the purpose of solid lubricant. During the trial assembly of flight spin motor to the bracket mounted on subsystem, one of the two fasteners failed such that the head of the bolt had shear...

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Bibliographic Details
Published in:Engineering failure analysis 2010-09, Vol.17 (6), p.1457-1465
Main Authors: Jha, Abhay K., Singh, Satish Kumar, Swathi Kiranmayee, M., Sreekumar, K., Sinha, P.P.
Format: Article
Language:English
Subjects:
Beta
Beta transus temperature
Bolting
Bolts
Bulging of transformed alpha in Ti alloy
Failure analysis
Failure of titanium fastener
Fasteners
Grain boundaries
Microstructure
Molybdenum disulfide
Titanium base alloys
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Summary:Titanium alloy fasteners are being used in space programme. These fasteners are coated with MoS 2, which serves the purpose of solid lubricant. During the trial assembly of flight spin motor to the bracket mounted on subsystem, one of the two fasteners failed such that the head of the bolt had sheared off the shank. Metallographic analysis carried out on the failed fasteners revealed variations in the microstructures all along the shank axis. Microstructure consisted of equiaxed primary alpha in transformed beta matrix within lower portion of the shank, while it was elongated primary alpha with little bulging all along prior beta grain boundaries as well as acicular alpha at some other location towards the head side, features, typical of, as if worked above beta transus temperatures. This paper highlights the details of investigations carried out on the failed fasteners.
ISSN:1350-6307
1873-1961
DOI:10.1016/j.engfailanal.2010.05.007