This study presents the microstructural characterization and evaluation of the mechanical properties of steel with different dual-phase microstructures, obtained by tempering ferritic-pearlitic LNE 500 steel. Its intercritical region and existing phases, as a function of temperature, were determined using the "THERMOCALC" software. With these results, samples were tempered from different temperatures to obtain varying volumetric fractions of ferrite and martensite. Microstructural characterization was performed using qualitative and quantitative metallography. The mechanical properties were determined by means of hardness, impact, and uniaxial tensile tests, which provided parameters such as yield strength, tensile strength, and total and uniform elongation, in addition to the work hardening exponent and the resistance coefficient of the treated steel. Results showed that heat treatments produced different microstructures. The greater presence of the martensitic phase contributes to improving the mechanical properties of hardened steel, such as hardness, impact energy absorbed, and mechanical strength without loss of ductility.