Propiedades mecánicas y resistencia al desgaste del acero AISI D2 con tratamiento convencional y criogénico profundo
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Date
2024-07
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Universidad Nacional de Trujillo
Abstract
El trabajo investigó porque el tamaño del carburo, observado mediante microscopía óptica (MO) y microscopia electrónica de barrido (SEM), afecto las propiedades mecánicas de resistencia a la fluencia y máxima a la tracción, dureza y resistencia al desgaste por abrasión del acero AISI D2 tratamiento térmico convencional (CHT) y tratamiento criogénico profundo (DCT). La microscopía SEM reveló un retraso en el engrosamiento del carburo debido al DCT, determinado por una mayor proporción de carburos finos o afinamiento de la estructura. Por otro lado, el afinamiento se debe en gran parte a la transformación de la austenita retenida en martensita observado en probetas DCT. El DCT incremento en 296 MPa la resistencia a la fluencia y en 351 MPa la resistencia máxima a la tracción, respecto del CHT, las durezas promedio de probetas de CHT fue de 672.35 HV10 y de 862.9 HV10 para DCT. Por Microscopia óptica (MO) evaluó la morfología, observando la presencia de Carburos Primarios globulares aislados y localizados en el centro y borde de grano del AISI D2 en tratamiento por CHT y DCT. Los EDAX puntuales de probetas CHT y DCT en la matriz y carburos, evidencian que en nuestro caso los CP son MC, el DCT inmediatamente después del CHT no altera la naturaleza química de los PC. Análisis de imágenes del tamaño de carburo en micrografías SEM a 1000 y 2000 determino el área de los PC, a 1000 fueron de 2.05 μm2 en CHT y de 1.46 μm2 DCT determinando el afinamiento de los carburos PC, a 2000, fue de 0.23 μm2 CHT y de 0.26 μm2 DCT, la determinación fue limitada. Los LSCs y SSCs se determinaron a 7000 el tamaño de carburo en CHT, los LSCs fue de 9.541μm2 en promedio y para SSCs fue de 1.72 μm2, por otro lado, para probetas DCT se determinó 4.56 μm2 para LSCs 0.9085 μm2 en promedio para los SSCs evidenciando el refinamiento de carburos. Los ensayos de desgaste abrasivo las DCT muestran un incremento de 3.67 mm3 respecto de la CHT, se atribuye a la casi ausencia de austenita retenida y a una distribución más homogénea de un mayor número de SCCs más finos en las probetas DCT.
The work investigated why the size of the carbide, observed by optical microscopy (OM) and scanning electron microscopy (SEM), affected the mechanical properties of creep resistance and maximum tensile strength, hardness and abrasion wear resistance of AISI steel. D2 conventional heat treatment (CHT) and deep cryogenic treatment (DCT). SEM microscopy revealed a delay in carbide coarsening due to DCT, determined by a higher proportion of fine carbides or structure thinning. On the other hand, the thinning is largely due to the transformation of retained austenite into martensite observed in DCT specimens. The DCT increased the creep resistance by 296 MPa and the maximum tensile strength by 351 MPa, compared to the CHT, the average hardness of CHT specimens was 672.35 HV10 and 862.9 HV10 for DCT. Using optical microscopy (OM), the morphology was evaluated, observing the presence of globular Primary Carbides isolated and located in the center and grain edge of the AISI D2 in treatment by CHT and DCT. The specific EDAX of CHT and DCT specimens in the matrix and carbides show that in our case the CPs are MC, the DCT immediately after the CHT does not alter the chemical nature of the PCs. Image analysis of the carbide size in SEM micrographs at 1000 and 2000 determined the area of the PCs, at 1000 they were 2.05 μm2 in CHT and 1.46 μm2 DCT determining the fineness of the PC carbides, at 2000, it was of 0.23 μm2 CHT and 0.26 μm2 DCT, the determination was limited. The LSCs and SSCs were determined at 7000 the carbide size in CHT, the LSCs was 9.541 μm2 on average and for SSCs it was 1.72 μm2, on the other hand, for DCT specimens 4.56 μm2 was determined for LSCs 0.9085 μm2 on average for the SSCs evidencing the refinement of carbides. The abrasive wear tests of the DCT show an increase of 3.67 mm3 with respect to the CHT, which is attributed to the almost absence of retained austenite and a more homogeneous distribution of a greater number of finer SCCs in the DCT specimens.
The work investigated why the size of the carbide, observed by optical microscopy (OM) and scanning electron microscopy (SEM), affected the mechanical properties of creep resistance and maximum tensile strength, hardness and abrasion wear resistance of AISI steel. D2 conventional heat treatment (CHT) and deep cryogenic treatment (DCT). SEM microscopy revealed a delay in carbide coarsening due to DCT, determined by a higher proportion of fine carbides or structure thinning. On the other hand, the thinning is largely due to the transformation of retained austenite into martensite observed in DCT specimens. The DCT increased the creep resistance by 296 MPa and the maximum tensile strength by 351 MPa, compared to the CHT, the average hardness of CHT specimens was 672.35 HV10 and 862.9 HV10 for DCT. Using optical microscopy (OM), the morphology was evaluated, observing the presence of globular Primary Carbides isolated and located in the center and grain edge of the AISI D2 in treatment by CHT and DCT. The specific EDAX of CHT and DCT specimens in the matrix and carbides show that in our case the CPs are MC, the DCT immediately after the CHT does not alter the chemical nature of the PCs. Image analysis of the carbide size in SEM micrographs at 1000 and 2000 determined the area of the PCs, at 1000 they were 2.05 μm2 in CHT and 1.46 μm2 DCT determining the fineness of the PC carbides, at 2000, it was of 0.23 μm2 CHT and 0.26 μm2 DCT, the determination was limited. The LSCs and SSCs were determined at 7000 the carbide size in CHT, the LSCs was 9.541 μm2 on average and for SSCs it was 1.72 μm2, on the other hand, for DCT specimens 4.56 μm2 was determined for LSCs 0.9085 μm2 on average for the SSCs evidencing the refinement of carbides. The abrasive wear tests of the DCT show an increase of 3.67 mm3 with respect to the CHT, which is attributed to the almost absence of retained austenite and a more homogeneous distribution of a greater number of finer SCCs in the DCT specimens.
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TECHNOLOGY::Materials science