New theoretical approach of the fracture ductility of steels and its relation with the microscopy structural characterization

It is well known that the formation of a highly hardening state of the standard steels is related with the improvement of its mechanical characteristics, which means an increment in the ductility of the fracture. Commonly, the ductility of the fracture is measured by means of mechanical methods involving large size and geometrical special shape of the sample. Satisfy these requirements in the initial steps of the development of a new material, or during the treatment for improving the hardness, is a dif ficult task. The present work shows the theoretical determination of the ductility of the fracture when the researchers have a small piece of the sample. Also, from the analysis of microscopy images, by the first time, it is demonstrated that an ultra-hardening state of the steel corresponds to a nano-fragmented dislocational structure in accordance to the theory.