Avaliação da substituição dos meios de resfriamento convencionais por solução polimérica no tratamento térmico de têmpera do aço SAE 4340

Abstract

This following work is purpose to examine the possibility of replacing the conventional means of cooling the heat treatment of hardening a polymer solution. From SAE 4340 steel samples subjected to heat treatment quenching followed by tempering, tensile, hardness and microstructural analysis were performed. In the tempering heat treatment, samples were cooled in a polymer solution with a concentration of 20% and 30% in mineral oil, and then were subjected to the tempering treatment. After tempering cross sections of the samples were removed for assay radial and longitudinal hardness and metallographic analysis. Specimens were prepared for conducting tensile test and comparison of mechanical properties. In the assay radial stiffness of the samples cooled polymer solution at 30% was one significant amount of 3.35% higher compared with conventional cooling with mineral oil and 1.36% in the longitudinal increased hardness. Also gave a significant value of 8.55% difference between the maximum breakdown force at the tensile test, and the 30% polymer solution had the best results. The safety at the time of the thermal bath also obtained good results, since the polymer solution is not combusted at high temperatures, than mineral oil. Environmental issue in the use of polymer solution was also satisfactory, as improper disposal of oil brings irreversible environmental consequences.