Novel Approach for the Development of Tailored Heterogenous Structures in Steel

A new strategy is introduced for developing architectured structures in medium carbon steels. The steel is initially decarburized within the austenitic range and quenched to produce a compositionally graded material with 0.4 wt.% carbon at the center and 0.1 wt.% carbon at the surface. Shear bands developed at the center of the sheet as a result of the cold rolling of the as-quenched microstructure. Subsequent annealing led to the development of nano-scale grains within the shear bands. By controlling the annealing temperature and time, it was possible to produce a wide range of bimodal grain-size distributions. Extended annealing tended to homogenize the material, leading to a fine grained ferrite/cementite microstructure.