Disk pressure testing of hydrogen environment embrittlement

The rupture appearances and pressures are compared for clamped disks, biaxially stressed to rupture under upward increasing pressures of helium or of an embrittling fluid such as gaseous hydrogen isotopes. Usually the downward surface is available for observation during the test in progress, but it can be exposed to a second embrittling medium. Factors studied include: (a) for the materials; chemistry (aluminum, cobalt, chromium, copper, iron, nickel, platinum, titanium, uranium, and zirconium, base), surface conditions, thermomechanical processing, and welding, (b) for the testing conditions (-196 to -4500C), H2 pressure, purity, and pressure increase rate. Low-cycle fatigue and delayed failure tests can also be conducted and discontinuous cracking monitored by various techniques, especially permeation. The disk pressure test (DPT) can be used for selection and quality control of bulk materials, protective coatings against hydrogen environment embrittlement (HEE), and their processing. Materials selection is made according to screening tests of increasing severity. The DPT shows evidence of other causes of embrittlement and their synergistic effects with HEE, which is quite important. Other advantages of DPT, such as sensitivity, versatility, rapidity, simplicity of operation and maintenance, safety, low cost of specimens, and equipment, are outlined and compared with other methods