Influencia de los tratamientos térmicos a temperaturas intercriticas IHT y tratamientos criogénicos y un posterior revenido de 15, 30 y 45 minutos a la resistencia a la fatiga de un acero AISI/SAE “4140”

Abstract

he interest in thermal treatments has been increasing notably in the last years thanks to the potential that has to generate significant improvements in the mechanical properties in the materials, in this project the influence of the treatments was studied to IHT intercritical temperatures in a steel AISI / SAE 4140. This project started with a spark spectrometer test, with this data then the critical temperatures were calculated according to the Kasatkin formula and the temperatures A1 and A3 were obtained, after the material was tempered in oil to a Temperature (770 ° C), (cryogenic) treatments were immediately carried out at subcero temperatures with determined times of 24 and 48 hours and afterwards a tempering with a time of 15, 30 and 45 minutes at a temperature of 400 ° C was performed, the material was subjected to tests Of resistance to fatigue based on the testing machine of the Franciscan district university José de caldas According to the norm. The corresponding fatigue tests were performed with two percentages of different loads, hardness analysis, hardness analysis, metallographic analysis, fracture analysis and microscopy without fracture and microstructure. The results were evaluated taking into account the material in the state of supply and the heat treated material. The results obtained demonstrate the effect of leaving the material at subzero temperatures with more time and how it affects the temper at each time to a material subjected to fatigue.