Effect of Cold Rolling on the Microstructural Evolution and Mechanical Properties of Fe-25Mn-3Si-3Al-0.3Nb TWIP Steel

The microstructural evolution, deformation mechanism and mechanical properties of Fe-25Mn-3Si-3Al-0.3Nb steel in the process cold rolling were studied by optical microscopy, scanning transmission electron X-ray diffractometry, tensile testing microhardness tests. A high-density dislocation structure a small number strain-induced twins appeared microstructure at 30% strain. At 50% strain, austenite increased conspicuously, lamella thickness decreased. 70% original grains clearly refined micro-shear bands twinning intersections to form large sub-grains, some sub-grains nanoscale. still remained single-phase during even if strain was as high 70%. plastic not changed through addition 0.3 wt.% Nb, both slipping fundamental mechanisms for steel. Furthermore, led drastic rise strength hardness steel, but remarkable decrease elongation. characteristics micropore aggregation fractures could always be observed on fracture surface static specimens with various strains.