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Microstructure Evolution of a Nickel-Base Alloy Resistant to High Temperature during Aging


Affiliations
1 Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), Universidad Nacional del Sur, Bahia Blanca, Argentina
 

In the present study, the microstructural evolution during aging at 1023, 1073, 1123 and 1173 K of a 35Cr-45Ni heat resistant alloy, produced in the form of centrifugally cast tubes, was characterized by means of light optical microscopy, scanning electron microscopy (SEM) with secondary and backscattered electron imaging, energy-dispersive X-ray spectroscopy (EDS) and Vickers hardness tests. The evolution of the Vickers hardness at 1023 K for aged samples shows that the microstructure is stable during the analyzed aging period. At 1073 K, the rate of increase in hardness is lower than 1023 K and this behavior would be associated with morphological changes observed in primary interdendritic carbides and secondary carbides in the matrix. At 1123 K and 1173 K, an atypical behavior in Vickers hardness curve is presented; where it can be seen that at certain aging times, the hardness decreases significantly. A microstructural analysis of these samples indicates that they have a region free of precipitates (near interdendritic edges) where the hardness is lower. Probably, these regions are areas poor in chromium.

Keywords

Microstructural Characterization, 35Cr-45Ni Alloy, Aging, Precipitation, Depleted Zones.
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  • Microstructure Evolution of a Nickel-Base Alloy Resistant to High Temperature during Aging

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Authors

Alberto Carlos Picasso
Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), Universidad Nacional del Sur, Bahia Blanca, Argentina
Cesar Armando Lanz
Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), Universidad Nacional del Sur, Bahia Blanca, Argentina
Matias Sosa Lissarrague
Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), Universidad Nacional del Sur, Bahia Blanca, Argentina
Aldo Daniel Garofoli
Comision de Investigaciones Cientificas de la Provincia de Buenos Aires (CICPBA), Universidad Nacional del Sur, Bahia Blanca, Argentina

Abstract


In the present study, the microstructural evolution during aging at 1023, 1073, 1123 and 1173 K of a 35Cr-45Ni heat resistant alloy, produced in the form of centrifugally cast tubes, was characterized by means of light optical microscopy, scanning electron microscopy (SEM) with secondary and backscattered electron imaging, energy-dispersive X-ray spectroscopy (EDS) and Vickers hardness tests. The evolution of the Vickers hardness at 1023 K for aged samples shows that the microstructure is stable during the analyzed aging period. At 1073 K, the rate of increase in hardness is lower than 1023 K and this behavior would be associated with morphological changes observed in primary interdendritic carbides and secondary carbides in the matrix. At 1123 K and 1173 K, an atypical behavior in Vickers hardness curve is presented; where it can be seen that at certain aging times, the hardness decreases significantly. A microstructural analysis of these samples indicates that they have a region free of precipitates (near interdendritic edges) where the hardness is lower. Probably, these regions are areas poor in chromium.

Keywords


Microstructural Characterization, 35Cr-45Ni Alloy, Aging, Precipitation, Depleted Zones.