Molecular Dynamics Simulation Study on the Effect of Mn on the Tensile Behavior of a Ferrite/Austenite Iron Bicrystal

The effect of Mn on duplex stainless steel is of great importance in the development of lean duplex stainless steel. In this paper, we applied molecular dynamics simulations to quantitatively investigate the effect of Mn addition on the tensile behavior of ferritic/austenitic (bcc–fcc) iron duplexes as a model system for duplex stainless steels. We found that dislocations originate at grain boundaries and most of the initial dislocations in the grain boundaries are Shockley partial dislocations. The temperature and the number of dislocations conform to a normal distribution relationship. In addition, the tensile deformation mechanism of duplex stainless steel is dominated by both phase transformation and dislocation activity. Mn can improve the tensile properties of the material by delaying the arrival of plastic deformation, increasing the dislocation density to improve the strength of the model, and promoting the phase transformation mechanism of fcc → hcp → bcc.