Effect of alloying additions on the hydrogen-induced grain boundary embrittlement in iron

Abstract

Using ab initio density functional theory calculations, we have investigated the influence of Mo, V and Pd on the H-induced grain boundary embrittlement in Fe. We find that, in the high impurity concentration systems, all of the three alloying elements facilitate H embrittlement at the Σ3 (111) [Formula: see text] grain boundary in Fe. The calculated binary effects of the H-X (X = Mo, V, Pd) couples are 0.063, 0.074 and 0.040 eV, respectively. On the other hand, in the large unit cell with low impurity concentration, both Mo and V can facilitate H embrittlement, and the binary effects of pairs are 0.152 and 0.164 eV, respectively. While Pd reduces the H embrittlement on the cohesion of the Fe grain boundary with the binary effect of - 0.1 eV. The H-X (X = Mo, V, Pd) interactions are interpreted by electronic structure analyses.

Hydrogen embrittlement II. Analysis of hydrogen-enhanced decohesion across (111) planes in α -Fe

“…In point of fact, E bind (n) is independent of E H 2 since the same term appears in the definition of E dis and cancels out of (12). The second task is to identify the positions and degeneracy of the trap sites in the cohesive zone.…”

Interatomic Fe-H potential for irradiation and embrittlement simulations

“…Otherwise, the second-nearest neighbors of the bcc iron would-due to thermal vibrations-experience the onset of the cutoff function [Eq. (8)], resulting in an unphysical increase in the Young's modulus of elasticity E = σ zz /ε zz , where ε zz denotes the normal tensile strain. By extending R to the middle of the second-and third-nearest-neighbor distances, this effect is avoided.…”

“…Hydrogen, although not soluble in iron in equilibrium, can be introduced into it by irradiation, nuclear decay, or chemical processes. Hydrogen is well known to cause embrittlement in iron and steel [1][2][3][4][5][6][7][8], which is a serious issue in, e.g., the automotive and nuclear industries. In the former, the high mechanical resistance desired from the body steels must often be traded off against their increased susceptibility to hydrogen embrittlement [9][10][11][12], while the nuclear processes in the latter will, on long time scales, induce hydrogen buildup in the reactor steels [13][14][15][16].…”

Ab Initio Study of the Combined Effects of Alloying Elements and H on Grain Boundary Cohesion in Ferritic Steels

“…Similarly, V has a cohesion enhancing effect on the same Σ11 GB [16,17]. Studies of the Σ 3(111) [110] bcc Fe GB indicated that V also has a cohesion enhancing effect [18], and, in the Fe-V-H system, it was found that there is no interaction between H and V at the GB, meaning that the presence of V does not affect the segregation of H to the grain boundary [19]. Mn alone was found to be embrittling at the Σ3(111)[110] [20] and γ-Fe Σ11(113)[110] [16] GBs.…”