Cryogenic creep testing methods are examined and evaluated. Because of the difficulty in testing at cryogenic temperatures and the relatively low creep rates that are observed at temperatures below 77 K, cryogenic creep systems must have very sensitive strain measurement capabilities and be extremely stable. A 0.05% change in load or a 0.001 mV change in strain signal over a 200 h test can change the observed creep rate by as much as 10% in high-purity aluminum. An evaluation is made based on experiments using several different loading techniques; comparisons are made to the results of others. Discussions of various data collection methods, test fixtures, strain measurement methods, temperature control methods, and material dependencies are also included.
