The iterative fragilization and the recovery of the mechanical properties, enphasized with the metod of Preaged Fracture

The problem of interaction of hydrogen with metals in general, and more particularly of hydrogen with steel takes more and more the form of a problem of dissolution of hydrogen in steel during its use. In the opinion of the Authors, the method best suited to this purpose appears to be the one exposed by Hyspecka and Mazanec in 1972, called ''Method of pre-aged fracture'', because it can well evidentiate the metal's proneness to the formation and growth of cracks by hydrogen, caused by the progressive penetration of hydrogen into the material. The progressive penetration of hydrogen will first cause a fall of toughness (which, expresses in per cent of reduction in area could reach values of z%=5) and, afterwards, with the prosecution of the discharge, a gradual and slow recovery, whereby the reduction in area reach again the initial levels (z%=60). The intensity of said phenomena appears to be bound to the values of discharge density and of stress, with the higher levels of discharge causing lesser damages, but in shorter times.