SYMPOSIA PAPER Published: 01 January 1963

Low-Cycle Fatigue of Ti-6Al-4V at −423 F


To determine the effects of various factors on low-cycle fatigue phenomena in connection with space vehicle design, axial tension fatigue tests up to 2000 cycles were conducted on titanium alloy, Ti-6Al-4V, at −423 F. The effects of changing the minimum-to-maximum load ratio and cycling speed for the range tested were slight. The fatigue strength of pressure-welded specimens was within 1 per cent of that of the base metal. Fatigue strengths at −423 F were 65 to 68 per cent higher than those at room temperature.

Two types of fractures were observed, depending on the fatigue life. A transition in the fracture appearance occurred between 700 and 2000 cycles in which the fracture changed from a cup-and-cone to a more typical surface-initiated fatigue fracture. Cycling below the ultimate tensile strength tended to raise the fatigue strength above the static tensile strength. Possible mechanisms are discussed.

Author Information

Hilsen, R., R.
Douglas Aircraft Co., Inc., Santa Monica, Calif
Yen, C., S.
Douglas Aircraft Co., Inc., Santa Monica, Calif
Whiteson, B., V.
Douglas Aircraft Co., Inc., Santa Monica, Calif
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Developed by Committee: E08
Pages: 62–75
DOI: 10.1520/STP44460S
ISBN-EB: 978-0-8031-6212-9
ISBN-13: 978-0-8031-6213-6