Evaluación del efecto de la temperatura de calentamiento en el tamaño de grano y las propiedades mecánicas del acero AISI 1018 en condiciones de normalizado

Abstract

The objective of this technical project was to evaluate the effect of the heating temperature on the grain size, tensile strength, hardness, and toughness of AISI 1018 steel, under normalized conditions. Sixty specimens were obtained, which were divided into five groups of twelve specimens, of which four were for traction, four for impact, and the last four for metallography and hardness. The specimens were subjected to a heat treatment of regeneration annealing with a residence time of two hours and then they were cooled in the air, the specimens intended for metallography and Brinell hardness were prepared in the Materials laboratory of the Faculty of Mechanics of the ESPOCH. The microstructures were analyzed and then the grain size was calculated and the hardness was measured. In addition, tensile and tenacity tests were carried out at the Carrocero Metal-Mechanical Productive Development Center in the province of Tungurahua. All procedures were performed under ASTM standards. In the results obtained, grain growth was evidenced by increasing the heating temperature, with this, the resistance and hardness decreased, but the toughness increased. In addition, it was observed that, at very high temperatures, close to the melting point, the structure and mechanical properties of the samples deteriorated due to the presence of widmanstatten ferrite. Additionally, the sampling error of the values of the quantitative variables of the tests carried out was determined, where errors of less than 10% were obtained, for which it is concluded that the requirements established in the standards used were met. It is recommended that in future research the heating temperature be varied to know its level of impact on the variability of the mechanical properties of 1018 steel.