Critical Assessment 38: Assessment of the intrinsic susceptibility to hydrogen embrittlement for qualification of steels

Figures & data

Figure 1. Schematic illustration of the method to determine the critical hydrogen concentration in sustained loading delayed fracture.

Figure 2. Dependence of K_ISCC on (a) tempering temperature and (b) internal strain estimated from X-ray line broadening for medium carbon Cr–Mo martensitic steels. (A) 0.04Nb, (B) 0.04Ti + 0.10V or (C) 0.10V + 0.04Nb (mass%) added to the base compositions [32]. (The numerical values in the abscissa of Figure 1(b) may not be correct.)

Figure 3. Strain-rate dependencies of (a) relative reduction in area in tensile tests for specimens containing [Peak^#1 + Peak^#2] hydrogen and only [Peak^#2] hydrogen, and (b) difference in Peak^#1 hydrogen, ΔC_H, between specimens strained to 0.08 with and without hydrogen for [Peak^#1 + Peak^#2] and [Peak^#2] series [41].

Figure 4. Temperature dependencies of (a) relative reduction in area in tensile tests for specimens containing [Peak^#1 + Peak^#2] hydrogen and only [Peak^#2] hydrogen, and (b) difference in Peak^#1 hydrogen, ΔC_H, between specimens strained to 0.08 with and without hydrogen for [Peak^#1 + Peak^#2] and [Peak^#2] series [41].

Figure 5. Tensile curves of high-strength steels given sustained loading at 0.8 of the tensile strength for 96 h with hydrogen charging. Tensile tests were conducted after degassing hydrogen at 303 K for 168 h. Tensile curves of specimens annealed at 473 K for 2 h after [H + prestress + 200°C] or without [Non-prestressin + 200°C] prestressing are also shown for comparison [44].

Figure 6. Tensile test after cyclic prestressing. (a) Schematic illustration of cyclic prestressing of different strain rates with/without hydrogen charging. Tensile test was conducted at constant strain rate. (b) Degradation of fracture strain at the tensile test affected by cyclic prestressing under hydrogen precharging [48].

Figure 7. (a) Hydrogen enhancement of the generation of defects on cyclic stressing with increasing stress cycles at different strain rates. (b) Relationship between HES and ΔC_H at different strain rates at prestressing [48].

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