Cast iron heat treatment: Identify how malleable cast iron is produced. Manufacturing route selection for obtaining malleable (toughened) cast iron from a base iron. Choose the correct process description.
Mechanical Engineering
Engineering Materials
Difficulty: Easy
Choose an option
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ABy adding magnesium to molten cast iron
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BBy quick chilling of molten cast iron
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CFrom white cast iron by prolonged annealing (heat treatment)
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DFrom grey cast iron by quenching in oil
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EBy alloying with nickel and chromium only
Answer
Correct Answer: From white cast iron by prolonged annealing (heat treatment)
Explanation
ConceptMalleable cast iron is obtained by heat treating white cast iron for long durations (annealing), transforming cementite into temper carbon and producing a tougher, malleable structure.
Why not the others?• Magnesium addition produces ductile (nodular) iron, not malleable iron.• Quick chilling makes white iron, not malleable iron.
Final AnswerFrom white cast iron by prolonged annealing (heat treatment)