Caracterización metalográfica y evaluación de las propiedades mecánicas de los aceros con y sin nitruración AISI 4340 y 34CRNIMO6, para la Empresa SERTECPET S.A.

Abstract

The aim of this study was to characterize metallographically and evaluate the mechanical properties of steels with and without nitriding AISI 4340 and 34CrNiMo6, for which specimens of these materials were obtained through the machining process, in relation to the evaluation of the mechanical properties the respective statistical analysis was performed. On the one hand, the chemical composition of both steels was analyzed by optical spectrometry analysis. On the other hand, the analysis of non-metallic inclusions was carried out, where the type, degree and series of inclusions were determined, as well as the comparison of the morphology with those described in ASTM E45-11. Then, a metallographic study of these steels was then carried out, where the photomicrographs were observed and compared with the help of the Metals Handbook, and the microconstituents of each steel were determined. In order to determine the mechanical properties of these steels, Rockwell hardness, impact and tensile tests were carried out using ASTM standards (E18-15, E23-18 and A370-21, respectively). For the statistical analysis, the design experiment 22 was used, resulting in a significant difference in the mechanical properties of the steels before the application of the nitriding treatment. Thus, AISI 4340 steel is advantageous in regard to toughness, creep stress, as well as ultimate tractive effort. In contrast, 34CrNiMo6 steel has advantages in terms of hardness and elongation. Additionally, no significant difference was observed between these mechanical properties after the application of nitriding. It is concluded that the application of nitriding treatment in these steels associates their mechanical properties, making interchangeability possible within production processes. It is recommended to expand evaluation parameters in order to increase the degree of research in this degree work.