PSI - Issue 59

Jesús Toribio et al. / Procedia Structural Integrity 59 (2024) 98–103 Jesús Toribio / Procedi a Structural Integrity 00 (2024) 000 – 000

100

3

L/2

x = a - r

R

r

a

A

D/2

Fig. 1. Axisymmetric notched geometries used in the experiments.

3. Fractographic analysis HAMD started at the notch tip, and fractographic analysis by scanning electron microscopy (SEM) showed the so called tearing topography surface or TTS (Fig. 2), resembling micro-damage (Toribio et al., 1991, 1992) and representing a slow crack growth mode (Toribio et al, 1991; Toribio, 1997). The TTS size decreases with the strain rate and it is influenced by the geometry in notched samples, reaching the location of the maximum hydrostatic stress point in quasi-static tests (Toribio et al., 1992), consistent with hydrogen transport by diffusion.

Fig. 2. Tearing topography surface (TTS).

4. Micromechanical Modeling of HAMD in Pearlitic Steel 4.1. HAMD by TTS in Pearlitic Steel

Two complementary terms are frequent in the scientific literature related to HE, HD, HAF or HAC, namely (i) hydrogen enhanced localized plasticity (HELP) and (ii) hydrogen enhanced decohesion (HEDE). In recent years Toribio (2018) formulated the two possibilities of HELP and HEDE as the dual micromechanisms of HAMD in