High hardenability of steels is related to the presence of alloying elements, which enable quenching in less severe media, which are characterized by low cooling rates. However, such alloying elements increase the cost of steel. Considering the possibility of developing quenching heat treatments with lower cost steels and achieving hardness values close to those of alloyed steels, this article aims to compare quenchants for low-carbon steels (SAE 1020 and SAE 8620), from different criteria. Among the cooling media, an aqueous cooling fluid formulated with surfactants and ionic additives, which is called Fastquench, was studied. In addition, brine, a solution of silica nanofluid, water and oils were used. The evaluation of the media was performed by analyzing the hardness profile in the steels after quenching, cooling curves and Grossman quench severity factor. The results show that among the evaluated media, brine had the highest severity, followed by Fastquench solution. Thus, the Fastquench solution formulated for this research has not been identified as an advantageous additive for quenching low carbon steels under the experimental conditions adopted since it did not reach results equal or superior to those of brine.