Comparison of the Various Test Methods for Studying the Hydrogen Sensitivity of Steels Used for Storage and Transport of Hydrogen Gas. Final Report, June 1, 1980-November 30, 1982.

摘要

Dynamic rupture and fatigue tests were conducted on twenty-five chrome-moly low alloyed steels. The dynamic rupture tests allow us to classify the hydrogen behavior of hydrogen pressure vessel materials with a high sensitivity and an excellent reproducibility. Moreover, a threshold index for hydrogen materials has been defined which is a function of the maximum wall stress. Embrittlement indices increase as the u.t.s. of the steels increase but pressure vessels with thick walls seem to be more susceptible to hydrogen than those with thin walls. Results of the fatigue test indicate that hydrogen considerably affects the number of cycles to crack initiation and to rupture. Correlations are now available between disk fatigue tests and real hydrogen pressure vessel fatigue tests. It is also possible to relate disk fatigue test data to fracture mechanics data. Theory shows that the good hydrogen behavior of a pressure vessel material is mainly due to a lack of reversible traps (detrimental traps) than to a higher number of irreversible traps (good traps). Increasing the irreversible traps number could be a way to improve the hydrogen behavior of such materials. The disk rupture test can be used as a screening test to select materials for hydrogen vessels. When hydrogen fatigue phenomena are supposed to occur, it is necessary to carry out disk fatigue tests to determine the critical number of cycles leading to crack initiation or to rupture. (ERA citation 08:054246)