Influence of cooling rate on the microstructure and properties of a new wear resistant carbidic austempered ductile iron (CADI)

Carbidic austempered ductile iron is a family of ductile cast irons produced with carbides that are subsequently austempered to exhibit excellent wear resistance, which is a new type of austempered ductile iron recently introduced in the market. Heat treatment parameters affect the microstructure of the carbidic austempered ductile iron. Among heat treatment parameters, cooling rate from homogenization temperatures to salt bath temperatures is the most effective, and is often easy to be neglected. Therefore, the effect of cooling rate on the microstructure and mechanical properties of carbidic austempered ductile iron was investigated. The experimental results indicate that with the increase of the cooling rate, the size of acicular ferrite became fine acicular ferrite gradually, the austenite content was retained, the impact toughness decreases and the hardness of the samples increases.