Molecular dynamics of hydrogen-induced BCC/FCC phase transition and cracking in plastic deformation of X80 duplex pipeline steel

GY Qiao and SY Huang and YG Liu and JT Sha and RX Bai and BH Che and FR Xiao and K Xu and LX Li, ENGINEERING FAILURE ANALYSIS, 170, 109324 (2025).

DOI: 10.1016/j.engfailanal.2025.109324

In this paper, the phase transition and plastic deformation cracking of M/A island with BCC/FCC phase boundary induced by hydrogen in X80 duplex pipeline steel have been studied by molecular dynamics simulation. Under tensile loading conditions, the number of holes and microcracks increases with the increase of tensile deformation and hydrogen concentration, however, the phase transition and dislocations are more susceptible to the influence of hydrogen concentration. There is a critical hydrogen concentration, below which hydrogen atoms are conducive to FCC -> BCC transition, dislocation generation and emission, BCC nucleation points increase, dislocation formation energy decrease, and the strain energy is released mainly through the hydrogen-enhanced local plasticity (HELP) mechanism. When the critical hydrogen concentration is exceeded, the FCC -> BCC transition and dislocation proliferation are inhibited by hydrogen atoms, and the strain energy is mainly released through microcracks during the deformation process.

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