Influence of stacking fault energy on deformation mechanism of Fe-Mn-CTRIP/TWIP steels

The deformation mechanisms of three TWIP steels with different stacking fault energy in Fe-Mn-C system were discussed in this paper.Results show that the microstructure is fully austenitic in quenching state and a few annealing twins in matrix of these steels.With the increasing of content of C and Mn,the stacking faulty energy of TWIP steel increases.When SFE is equal to 7 mJ/m2,there are a mass of e-matensite in TWIP steel after deformation and the volume of e-martensite enhanced with the increasing of strain,which shows the dominant TRIP effect.When SFE is equal to 12 mJ/m2,strain induces γ→e→α or γ→α phase transformation and a few mechanical twins,which shows the TRIP and TWIP effects.When SFE is equal to 18 mJ/m2,a large amount of mechanical twins forms after deformation,which expresses single TWIP effect,resulting in a higher tensile strength(up to 851 MPa) and elongation(49%).With the increasing of SFE,the fracture mechanism of three TWIP steels turns to ductile fracture with dimples from brittle fracture.