SYMPOSIA PAPER Published: 01 January 1969

Low-Cycle Fatigue Study of Columbium Alloy D-43


A machine was developed to study the low-cycle fatigue characteristics of refractory metals in vacuum at high temperatures. Operating capability included temperatures up to 1400 C, loads to 4.45 × 104 N (10 ksi), and frequencies from static to 10 Hz. The machine operated in a push-pull mode and was stroke controlled.

To minimize material required for testing, grips were designed to operate at nearly the same temperature as the specimen. A typical specimen geometry was a rod, 76 mm long with a test section 12.7 mm long and 5.18 mm in diameter.

A series of tests was performed on a columbium alloy, D-43, at temperatures ranging from 20 to 1204 C and cyclic plastic strains from 0.3 to 4 percent. Data at 20, 871, and 1093 C revealed that D-43 conformed to the Coffin-Manson equation, wherein cycles to failure was related to plastic strain range by a power function.

The plastic strain resistance was found to increase with increasing temperature and to exhibit a maximum around 871 C. Up to 1024 C cyclic strain resistance remained better than or equivalent to that at room temperature.

Posttest examination of specimen revealed ductile, transgranular failures at all temperatures.

Author Information

Swindeman, RW
Union Carbide Corp. for the U.S. Atomic Energy Commission, Oak Ridge, Tenn.
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Developed by Committee: E08
Pages: 31–41
DOI: 10.1520/STP33647S
ISBN-EB: 978-0-8031-4581-8
ISBN-13: 978-0-8031-0016-9