Molecular dynamics simulation of porous layer-induced stress in Fe single crystal

Pipeline steel in soil containing water could induce a macro tensile stress, leading to stress corrosion cracking (SCC). Porous layer-induced stress in Fe single crystal with various vacancy distributions on the surface layer is studied using molecular dynamics. The results show that Fe single crystal with one end fixed and a porous layer on the surface is deflected toward the porous layer during relaxation, resulting in a macro tensile stress. There is a maximum tensile stress in the matrix near the interface between the porous layer and the matrix resulting from the porous layer. The average stress on the porous layer σxx(d), which is calculated based on the measured deflection, increases with the increase of the maximum vacancy concentration CV on the top surface and the relative depth of the porous layer d/B. And the macro tensile stress σxx(B) on the cross section of the sample increases also with the increase of CV and d/B. σxx(B) is approximately four times smaller than σxx(d).