Classification of cast irons by carbon content Iron–carbon alloys containing 1.7 to 4.3% carbon are classified as which type of cast iron with respect to the eutectic composition (≈4.3% C)? Choose the correct option.

ConceptThe eutectic composition for Fe–C cast irons is about 4.3% C. Cast irons with less than this value (≈2.0–4.3% C; many texts start at ≈1.7%) are termed hypo-eutectic. Those with carbon content greater than 4.3% are hyper-eutectic.

Final AnswerHypo-eutectic cast irons