Electrochemical hydrogen permeation measurement during cyclic stress testing of a ferritic chromium steel

In the present work, the hydrogen diffusion during cyclic stress testing in the ferritic chromium steel 1.4521 (X2CrMoTi18-2) is investigated. Therefore, electrochemical hydrogen permeation measurements are carried out on a hollow cylinder geometry. Simultaneously an alternating stress is applied using a stress ratio of R=-1. At low stress amplitudes, no influence on the diffusion behaviour of hydrogen is found. At a higher stress amplitude, close to the macroscopic yield strength, a delayed hydrogen permeation by a factor of two is observed. It is postulated that this observation is a result of the nucleation of new hydrogen traps during the measurement. Hydrogen content measurements using carrier gas hot extraction support this hypothesis. In this work, the change in hydrogen diffusion behaviour as a result to cyclic mechanical stress is investigated. For this purpose, electrochemical hydrogen permeation measurement is used and applied to an axially loaded hollow cylinder geometry to abstract the industrial application of a pipe. image