Designing with Titanium
Designing with Titanium
(OP)
I am presently in the process of designing a pressure vessel for sonar equipment to be used in depths up to 6km. After extensive manual calculations and FEA analysis we fabricated parts from the Ti-6Al-4V titanium alloy and experienced several catastrophic failures in testing, which seem to indicate that this titanium alloy reacts as a brittle material in regions of stress concentration. Has anyone had experience with this alloy?





RE: Designing with Titanium
i haven't heard of 6Al4V being brittle, its a fairly commonly used alloy. check properties in Mil Hdbk 5 (or AR MMPDS).
"For maximum toughness, Ti-6Al-4V should be used in the annealed or duplex-annealed conditions" ... in round numbers annealed ftu = 120ksi, heat treated ftu = 160 ksi.
"Its toughness in the annealed condition is adequate at temperatures down to -320F."
"Under certain conditions, titanium, when in contact with cadmium, silver, mercury, or certain of their compounds, may become embrittled.
Refer to MIL-S-5002 and MIL-STD-1568 for restrictions concerning applications with titanium in contact with these metals or their compounds"
is it practical to use interference bushes ?
Quando Omni Flunkus Moritati
RE: Designing with Titanium
RE: Designing with Titanium
have you looked (with an SEM) at the fracture surface ? maybe a pre-existing defect initiated the failure ?
how cold does it get (6 km down) ?
have you done an NL FEA ? i wonder how the material can strain in the localised tension fiedl when the bulk structure probably has a pretty damn big compression stress. maybe it's this constraint that makes it look (or behave) brittle ?
i imagine we're dealling with a fairly thick section ?
Quando Omni Flunkus Moritati
RE: Designing with Titanium
RE: Designing with Titanium
RE: Designing with Titanium
TTFN

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