Effect of helium environment on the creep rupture properties of Inconel 617 at 10000C

The effect of oxygen contents in helium and in vacuum on the creep rupture properties of Inconel 617 has been investigated at 10000C under the stress of 3.5 kg/mm2. The main results are as follows. 1) The creep rupture properties in 99.9999 and 99.995 percent helium and in high vacuum are almost the same as those in air. 2) The oxygen in helium causes a remarkable decrease of the creep rupture time and similar effect of oxygen is also found in the controlled pressure of air. 3) The effect of oxygen on the creep rupture properties is attributable to the decarburization which tends to decrease the high temperature strength. (U.S.)