Biaxial Creep of Materials in Lithium: Development of Apparatus and Trial Run with Type 304l Stainless Steel

摘要

Specific biaxial stress in a cylindrical capsule can be achieved by controlling capsule wall thickness and pressure inside the capsule. Since creep is limited to a thin wall section of the capsule, several stresses can exist simultaneously in the same capsule if sections of the capsule wall are machined to different thicknesses. As creep occurs, the diameters of the thin sections increase, while the length of the capsule does not change significantly. Creep specimens of the materials to be tested under this program were made by fabricating cylindrical capsules designed to be filled with pressurized lithium. An apparatus to measure the biaxial creep of alloys in contact with lithium up to 2500F was constructed and successfully demonstrated. The creep apparatus consists of a high-vacuum tube furnace with a uniform temperature zone and auxiliary argon pressure systems, and is capable of holding four capsules. Strain is measured by stopping the test periodically and measuring the diameters of the thin sections of the capsule.