Titanium alloys are employed in the design of superconducting magnet support
systems for their high mechanical strength associated with their low thermal
conductivity.But their use requires a careful attention to their crack tolerance
at cryogenic temperature. Measurements have been performed on two extra low
interstitial materials (Ii-5Al-2.5Sn ELI and Ti-6Al-4V ELI) with different
thickness and manufacturing process. The investigation includes the tensile
properties at room and liquid helium temperatures using smooth and notched
samples. Moreover, the fracture toughness has been determined at 4.2 K using
Compact Tension specimens. The microstructure of the different alloy and the
various fracture surfaces have also been studied. After a detailed description
of the experimental procedures, practical engineering characteristics are given
and a comparison of the different titanium alloys is proposed for cryogenic
applications.
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