Efecto del tratamiento sub-cero sobre la microestructura y dureza de fundiciones blancas alto cromo
AUTOR(ES)
Hernández, Eliseo, Leiva, Ricardo, Escobar, Alex, Ordoñez, Stella
FONTE
Matéria (Rio J.)
DATA DE PUBLICAÇÃO
19/07/2018
RESUMO
ABSTRACT The effect of the sub-zero treatment temperature on the transformation of retained austenite to martensite in two high chromium white cast irons (ASTM A532 Class II Type B) was studied. The sub-zero treatment applied to each alloy in the as cast condition was performed at -40, -65 and -180 ° C for 10 minutes; after the holding time was completed the samples were cooled to room temperature. The microstructure of the as cast condition was analyzed by optical microscopy (LOM) and scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS) analysis was also performed with the aim to identify the microconstituents initially present in each alloy. The metallographic characterization of the specimens subjected to sub-zero treatment was performed by optical microscopy. Furthermore, Brinell hardness was measured in the as cast and sub-zero treated samples. The alloys studied have important differences in chemical composition, mainly in the molybdenum and copper content, which mainly determine its microstructure. The results showed an increase in the hardness of both alloys with decreasing treatment temperature; which is due to the fact that the amount of retained austenite transformed to martensite increases as the martensite finish temperature (Mf) is reached. It was also observed that a higher molybdenum content produces a metastable austenitic matrix in the as cast samples. Furthermore, the effect of Mo and other alloying elements substantially stabilizes the austenite, obtaining low amounts of martensite after the sub-zero treatment, even at -180 ° C.
Documentos Relacionados
- Efecto del V y el Si Sobre la Microestructura de Depósitos Realizados con Electrodos Tubulares Revestidos de Alto Contenido de Mn (Hadfield)
- Efecto del tratamiento térmico sobre la resistencia mecánica, corrosión intergranular y exfoliación de la aleación de aluminio 7075
- Efecto de la Composición Química del Metal de Aporte y del Calor Aportado Sobre la Microestructura y las Propiedades Mecánicas de Juntas Soldadas de Aceros Inoxidables Dúplex
- Efecto del secado térmico y el tratamiento alcalino en las características microbiológicas y químicas de biosólidos de plantas de tratamiento de aguas residuales domésticas
- Efecto del catión, del anión y del co-ión sobre la agregación de líquidos iónicos en solución acuosa