This paper discusses the formation of microstructures with different volume fractions, as an outcome from a specific heat treatment, with the following phases: ferrite, martensite, bainite and retained austenite. For the microstructure characterization we developed a chemical etching that allows us to distinguish the phases by optical microscopy. The process was also accomplished by scanning electron microscopy with the objective of analyzing the active mechanisms of fracture and transmission electron microscopy with the aim of determining the dislocation substructures formed during the fatigue test. The evaluation of the mechanical properties is carried out based on the results of the tensile and fatigue tests. The experimental results show that appropriate heat treatments can contribute to a significant improvement of the mechanical properties of the steel. In this process it is essential to control the volume fraction, phases morphology, and grain size.
