Estudio experimental de la resistencia al desgaste erosivo en un acero AISI 4140 endurecido por el tratamiento de borurización.

Abstract

En el presente trabajo de investigación, se construyó una máquina de erosión por partícula sólida a alta temperatura, mediante la técnica de despliegue de funciones de calidad (QFD) y empleando la norma ASTM G76, obteniéndose una máquina funcional para estudiar el desgaste erosivo por partícula sólida en un acero AISI 4140 y AISI 4140 borurado. La caracterización mecánica de las capa de boruro de hierro fue evaluada por la técnica de indentación instrumentada Berkovich, la técnica de difracción de rayos X y la técnica de microscopía electrónica de barrido. Basándose en los resultados obtenidos de indentación instrumentada Berkovich, se estimaron los esfuerzos residuales en la capa borurada tipo Fe2B, mediante la ecuación de Lyakhovich. Finalmente se realizaron los ensayos de erosión por partícula solida a temperatura amiente ya la temperatura de 673 K sobre un acero AISI 4140 y ASISI 4140 borurado, sometidos a los ángulos de incidencia de 30°,60° y 90! Pata determinar la tasa de erosión que se origina bajo estas condiciones, la pérdida de masa que se genera y los mecanismos de falla que se obtienen a estos ángulos de incidencia.

Abstract In this study, high temperature and room temperature erosion tests are performed on AISI 4140 steels and AISI 4140 borided steels.. With the employment of scanning electron microscope, energy-dispersive X-ray spectroscopy, and Berkovich indentation testing techniques, detailed microscopic analysis of samples is conducted to reveal the underlying causes affecting the anti-erosion performance of these steels. The erosion tests were performed using a machine developed according to some parameters of the ASTM G76-95 standard. The samples have a rectangular shape with dimensions of 25 x 25 mm and 10 mm in thickness. The abrasive were used; Aluminum oxide (Al2O3) with a particle size 60 μm and angular granulometry, The tests were performed using three different incident angles 30°, 60° and 90° with an approximate particle speed of 30 ± 2 m/s and a flow rate of 40 ± 1 g/min. 3 minutes per sample was the exposure time of the test,to determine the amount of mass loss. From the results for room temperature tests by solid particle erosion, made in AISI 4140 steel and subjected to an impact angle of 30 ° the highest rate of erosion Angles 90 ° and 60 is obtained in comparison °. This confirms that for ductile and subjected to erosion of small impact angles (30 °) material, predominantly plastic deformation and erosion is high in the material surface. The mechanisms of post-test fails present erosion were cut and plow. Also in the AISI 4140 borided steel , and subjected to erosion testing under an impact angle of 90 ° , the highest rate of erosion as compared to the Angles of 30 ° and 60 ° was obtained . The material removal was raised by cracking and fracture predominantly characteristic of brittle failures at high angles of impact (90°). For high temperature erosion test and at different angles of impact, estimates of the erosion rate values are decreased (between 12 and 15 %) compared to the results obtained in the tests performed at room temperature (Consider both AISI 4140 steel and AISI 4140 borided). In both materials, surface failure mechanisms caused during erosion test were similar to those obtained at room temperature