Abstract
A new type of cryogenic temperature fatigue testing machine was installed in 1983 at the National Research Institute for Metals, Tukuba Laboratories. This machine is featured by the continuous operation at 4K without replenishing liquid helium. A closed-loop helium recondensation system enables a long-term fatigue test at 4K longer than 1, 000h. The total operation time reached 5, 500h in these seven years.
