Numerical analysis on hydrogen diffusion and concentration in solid with emission around the crack tip

Effect of Low-Temperature Sensitization on Hydrogen Embrittlement of 301 Stainless Steel

“…It is known that hydrogen tends to accumulate and embrittle the elastic-plastic boundaries of high-strength steels [32], and this embrittlement becomes more severe at the locations of stress concentration, such as a notch [33,34]. Moreover, a notch can produce a triaxial stress state, and limits the plastic deformation ahead of the notch tip.…”

“…Regarding the hydrogen-charged specimens, extensive cleavage-like fracture together with numerous secondary cracks was observed in the CR-300H specimen (Figure 5c), while the CR-450 specimen mainly exhibited intergranular fracture (Figure 5d). It is known that hydrogen tends to accumulate and embrittle the elastic-plastic boundaries of high-strength steels [32], and this embrittlement becomes more severe at the locations of stress concentration, such as a notch [33,34]. Moreover, a notch can produce a triaxial stress state, and limits the plastic deformation ahead of the notch tip.…”

Hydrogen Diffusivity in the Welding Zone of Two High Strength Experimental Microalloyed Steels

“…The problem with hydrogen is its low solubility in the lattice, its high power to be adsorbed, absorbed and diffused and its ability to localize at internal sites such as voids, precipitates, inclusions, grain boundaries and regions with high stresses; 5,14,15) as well as its ability to react with certain elements to form hydrides. The driving force for hydrogen diffusivity is a difference of activities presented as a concentration gradient, stress gradient, electrical gradient and temperature gradient.…”

“…23) In short, hydrogen diffusion in steel is influenced by two factors: a) a difference of chemical activities and b) hydrogen traps (grain boundaries, solute atoms, voids, inclusions, precipitates, phases and dislocations). 12,15,24) Although residual stress and yield stress are the important parameters to produce HIC, for example, it has been shown that with increased yield stress, increases the accumulation of hydrogen in the area of crack tip corresponding to the zone where is located the maximum triaxial tensile stress; 5,6) all mechanisms that attempt to explain the damage caused by hydrogen, agree that for this phenomenon to exist requires that the hydrogen diffuses towards a high activity zone. Thus, to study the susceptibility of a steel or a microstructure to HIC, hydrogen diffusivity should be determined.…”

“…[1][2][3][4] It is known and accepted that increasing the strength of steels also increases the susceptibility to hydrogen induced cracking (HIC). [5][6][7] In particular, it is known that the microstructure and hardness of the heat affected zone (HAZ) of steel welds have a great influence on HIC. For example, the martensite formation is related to this phenomenon, [8][9][10] so to avoid or mitigate HIC, materials are selected and/or the welding process is designed to inhibit the formation of this microconstituent.…”