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Why can cast iron be more brittle than wrought iron?

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How iron is turned into steel — iron processing Iron ore is one of the most abundant elements on Earth, and one of its primary uses is in the production of steel. When combined with carbon, iron changes character completely and becomes the alloy steel.

Cast iron is more brittle than wrought iron primarily due to its significantly higher carbon content. While wrought iron typically contains less than 0.1 percent carbon, cast iron contains between 2 and 4 percent.12

This high carbon concentration, often present in the form of graphite flakes or clusters, creates internal structural weaknesses. In gray cast iron, for example, these graphite flakes act as crack-inducing sites that reduce the material's overall strength and malleability. Because of this composition, cast iron lacks the ductility of wrought iron—a fibrous, relatively pure form of iron that can be hammered, twisted, or stretched without shattering. Consequently, while wrought iron is prized for its toughness and ability to withstand impact, cast iron is prone to shattering if dropped and is generally unsuitable for applications requiring high shock resistance.13425