Molecular dynamics simulation-based representation of intergranular fracture processes in austenitic steel

• Published in: Journal of materials research 2022-12, Vol.37 (23), p.4153-4168
• Main Authors: Wei, Limin, Zhou, Fei, Wang, Shuo, Hao, Weixun, Liu, Yong, Zhu, Jingchuan
• Format: Article
• Language: English
• Subjects: Applied and Technical Physics; Austenitic stainless steels; Biomaterials; Chemistry and Materials Science; Crack propagation; Criteria; Dislocation density; Ductile fracture; Ductile-brittle transition; Grain boundaries; Inorganic Chemistry; Intergranular fracture; Materials Engineering; Materials research; Materials Science; Molecular dynamics; Nanotechnology; Nucleation; Plastic deformation; Propagation; Simulation
• ISSN: 0884-2914; 2044-5326
• DOI: 10.1557/s43578-022-00780-2

In this paper, the propagation behavior of grain boundary crack in austenitic steel at different temperatures is investigated by molecular dynamics simulation. The evolution of microstructure and dislocations during crack propagation is observed. As the temperature increases, the peak dislocation density of the system increases and the time of dislocation nucleation advances (the time at which the strain is 0% is defined as 0 ps). However, the dislocation variation at 873 K does not follow this pattern, which may be related to the diffuse distribution of disordered atoms. Additionally, the crack propagation can be divided into three stages: (I) passivation, (II) rapid extension and (III) fracture. The crack propagation rate is negatively correlated with the peak dislocation density in stage I. As the temperature increases, the crack propagation manner undergoes a transformation process of brittle, ductile–brittle mixture, and ductile. The fracture mode and crystal plastic deformation form are predicted using Rice criterion and Tadmor-Hai criterion, respectively. It is indicated that the theoretical predictions are consistent with the simulation results. Graphical abstract