The use of cyclic DJ q as a parameter for fatigue initiation of X52 steel
Résumé
The concept of DJ cyclic has been extended to fatigue initiation emanating from notch. The parameter is then named DJ q. Validation of this parameter is made by fatigue tests made on Roman tile specimens made in X52 pipe steel. Here, fatigue initiation is detected by acoustic emission. It has been found that the fatigue initiation decreases after hydrogen absorption. This can be explained by interaction of hydrogen and plasticity as can be seen for tensile and fracture behaviour of X52 steel after introduction of hydrogen.