Deformation characteristics of nanocrystalline TWIP steel under uniaxial tension and compression

Abstract

Molecular dynamics simulations have been carried out to investigate the deformation behavior of nanocrystalline TWIP steel under strain-controlled tensile and compressive loading. All simulations were performed using the interatomic potential proposed by Wang et al. (2017). The crystallographic texture and three-dimensional orientation mapping of atomic structures were characterized according to the Euler angles of individually oriented atoms. A clear dependence of deformation twinning on grain orientation has been found for tension- and compression- deformed samples. Both homogeneous and heterogeneous nucleation of deformation twins is detected in case of a large grain size of about 52 nm. While in sample with a small grain size of 12 nm, deformation twins have nucleated heterogeneously from grain boundaries. The results also revealed that the volume fraction of nanotwins and texture evolution are strongly dependent on the loading direction. In tension, nanotwins were observed in a wide range of grain orientation but in compression some special grains experienced twinning behaviour. Twinning was seen for grain orientation near <001> direction in compression-deformed sample. It was also revealed that volume fraction of nanotwins were increased by increasing deformation percentage during uniaxial compression and tension loading.