Effect of cold rolling on recrystallization and tensile behavior of a high-Mn steel

The microstructure evolution in an Fe-17Mn-1.5Al-0.3C steel processed by cold rolling with subsequent annealing was studied. Cold rolling was accompanied by a significant increase in dislocation density and the development of deformation twins followed by the formation of microshear bands. The recrystallization of cold rolled specimens was observed at temperatures of T ≥ 873 K for annealing times of 30 min. An increase in the cold rolling strain increased the density of recrystallization nuclei leading to fine-grained microstructure and accelerated the recrystallization kinetics. The steel with partially recrystallized microstructure exhibited the yield strength and total elongation above 600 MPa and 30%, respectively. The same level of strength along with total elongation above 60% was achieved by the development of a uniform fine-grained recrystallized microstructure with a grain size below 1 μm in the sample subjected to cold rolling to a strain of 3 followed by an annealing at 873 K for 1 h. The influence of the initial cold rolling strain on the hardness after cold rolling and on the recrystallized fraction were formulated using power law relationships, whereas the yield strength after annealing was found to be predictable by consideration of dislocation density in non-recrystallized grains and size of recrystallized grains.