Influence of heat treatments on microstructure of austempered ductile iron
作者:
AranzabalJ.,
GutierrezI.,
UrcolaJ. J.,
期刊:
Materials Science and Technology
(Taylor Available online 1994)
卷期:
Volume 10,
issue 8
页码: 728-737
ISSN:0267-0836
年代: 1994
DOI:10.1179/mst.1994.10.8.728
出版商: Taylor&Francis
数据来源: Taylor
摘要:
AbstractThe influence of temperature and time of austempering on a nodular cast iron austenitised for 30 min at 900°C has been investigated using optical and transmission electron microscopy. The carbon content of the austenite has been evaluated by measuring the lattice parameter via X -ray diffraction. The structure consisted of bainite containing retained austenite, the amount of which increased, and the carbon content of which decreased, with increasing austempering temperature. No carbides were detected in the materials austempered at 300 and 370°C for up to 2 h, which contained only bainite and austenite. After austempering at 410°C and cooling to room temperature a certain amount of martensite was always detected. After long times at this temperature the austenite decomposed to ferrite and complex carbides. Martensite formation seems to be promoted by the decrease in the carbon content of austenite due to the precipitation ofɛcarbide homogeneously within it. During long austempering treatments at 410°C complex carbides are formed, probably from theɛcarbides precipitated in the austenite.MST/1926
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