Avaliação da relação dureza e tenacidade dos aços SAE 1045, SAE 4140 e SAE 4340 submetidos à resfriamento contínuo em solução polimérica aquosa

Abstract

The steels under study in this work are present throughout the industrial sector of the country, and the use of tempering occurs with the purpose of increasing the hardness of the materials, producing more reliable products and components, with greater resistance to wear, resistance to fatigue and resistance to dynamic and static loads. For the formation of martensite, a microstructure obtained by the tempering process, it is necessary to heat the steel to temperatures above the austenitization temperature, followed by a rapid cooling. The cooling should be fast enough to guarantee the formation of the martensite, but not so fast to avoid the occurrence of cracks or deformations, resulting in the part being unusable and discarded. Therefore, this work explores the use of the polymeric solution as a cooling not so severe, that does not generate cracks in the material, but that gives good hardness results, in addition to a good hardness and tenacity relationship, which was successfully obtained after the impact analyzes, hardness profiles and metallographies, being a stable cooling solution, non-flammable, without smoke generation, odor and incrustations in the treated samples, in addition to being effective in obtaining martensitic microstructure. The SAE 4340 steel stands out with the best hardness and tenacity relationship obtained among the studied steels, and the 30% polymer solution as the best solution used, with the highest tenacity values obtained in the steels, without drop in their hardness profiles.