Influence of two-step austempering process on mechanical properties and wear resistance of carbidic austempered ductile iron (CADI)

CADI (Carbidic ADI) - ausferritic ductile iron containing carbides - is a relatively new engineering material which exhibits excellent wear resistance and adequate impact strength. In this work the influence of two-step austempering process on selected properties of CADI cast iron was examined. Two batches of samples were initially austenitized at 900°C for 60 min. The first batch of the samples was austempered conventionally by single-step process in a salt bath at 4 different temperatures: 300, 330, 360 and 390°C for 120 min. The second batch was processed by two-step austempering process, first in a salt bath at 260°C for 10 min and subsequently in second salt bath at temperatures 300, 330, 360 and 390°C for 120 min. Results show that two-step austempering process improves impact strength and wear resistance of CADI compared to conventional heat treatment process.

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