Cast Iron vs Wrought Iron: What’s the Difference?

In terms of mass, iron is the most common element on Earth. Research shows iron accounts for 35% of Earth’s total mass, followed by oxygen at 30% and silicon at 15%. It’s found in the Earth’s outer core as well as its inner core. Once mined and harvested, though, iron is often processed into either cast iron or wrought iron. While both types of iron consist of pure iron, they aren’t necessarily the same. So, what’s the difference between cast iron and wrought iron?

What Is Cast Iron?

Cast iron is an iron alloy consisting of approximately 2% to 4% carbon along with trace amounts of silicon, manganese and other elements. It’s called “cast iron” because it’s made through casting.

To produce cast iron, metalworking companies smelt raw iron or pig iron. Once smelted, the molten iron is mixed with carbon and other alloys. The newly mixed iron solution is then transferred into molds of a pre-fixed shaped. After the iron solution has cooled, it’s removed from the mold for use as cast iron.

What Is Wrought Iron?

Wrought iron, on the other hand, consists primary of iron with 1% to 2% slag. When iron is smelted, slag is created as a byproduct. While the exact composition of iron slag varies, it typically consists of elements like silicon, phosphorus and sulfur.

To produce wrought iron, metalworking companies heat and bend or work iron multiple times. After heating the iron, a metalworking company will bend or work it using a hammer. Next, they’ll reheat the iron, followed by performing a second round of bending or working. It’s not uncommon for wrought iron to undergone a half-dozen cycles of heating and working.

Differences Between Cast Iron and Wrought Iron

Aside from their nuances in composition, there are other differences between cast iron and wrought iron. As previously mentioned, they are produced in different ways. Cast iron is made through casting, whereas wrought iron is made by heating and bending or working iron multiple times. As a result, most metalworking companies will agree that cast iron is easier to produce than its wrought iron counterpart.

Wrought iron is also stronger than cast iron. Each time wrought iron is heated and worked, it becomes a little stronger. Because of its strength, wrought iron is often used in commercial applications.

While wrought iron is stronger, cast iron is harder than its counterpart. It’s able to resist deformation under pressure or stress with greater ease than wrought iron.

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