ANS:C - white cast iron

Malleabilization heat treatment is typically performed on white cast iron. White cast iron is characterized by its high carbon content and the presence of cementite (Fe3C) in its microstructure, which makes it hard and brittle. Malleabilization heat treatment involves heating the white cast iron to a temperature below the eutectoid temperature (the temperature at which austenite begins to form from the iron-carbon alloy), typically between 850°C and 950°C, and holding it at this temperature for an extended period. This process causes the cementite to decompose into graphite flakes dispersed in a matrix of ferrite or pearlite, which imparts ductility and malleability to the material. Spheroidal graphite cast iron, on the other hand, already possesses good ductility due to its graphite nodules dispersed in the matrix, and it typically undergoes different heat treatments such as annealing, normalizing, or quenching and tempering to achieve desired properties. Therefore, malleabilization heat treatment is performed on white cast iron.