Many people believe that the term ‘cast iron’ alludes to early ironwork, or it was always ‘wrought iron’, or both may be correct. These are all a misconception, and the basic difference between cast and wrought iron is simple. The former is iron in a molten form that is poured into a mold, and then allowed to cool and solidify. The latter is iron heated and worked with tools.
The “cast” part in “cast iron” refers to the output made by way of the metal casting process, and the “wrought” part in “wrought iron” refers to the output shaped by hammering. Of course, their names themselves define how they are formed. However, that is a simple distinction. Let us dwell deep into this topic and find out the main differences between them.
Cast Iron
It is made by smelting and mixing iron ore with scrap metals as well as other alloys. Once poured into the mold, the liquid mixture is allowed to cool in time and harden. Owing to the higher carbon content, it hardens as one heterogeneous alloy, which means it has many constituents or multiple materials in different stages, inside the microstructure of it. This quality also affects cast iron’s physical properties.
As opposed to steel or wrought iron, cast iron is extremely brittle, relatively hard as well as non-malleable. Cast iron cannot be bent, hammered, or stretched into shape. Cast iron’s weak tensile strength also means it will fracture, before it distorts or bends. However, it features fine compression strength and was prominently used in the construction segment prior to the advent of steel sectors in the early twentieth century.
Casting is a considerably less labor-intensive process than making wrought iron and was one of the prominent forms of production through the eighteenth and nineteenth centuries. While cast iron has been replaced to a great extent by steel in the segment of construction, it is still employed for several industrial applications.
Wrought Iron
Cast and wrought iron also differ in material compositions. The latter is composed mainly of iron with one to twenty percent of added slag. During manufacture, it is removed from the heat and then worked with (while still hot) in order to achieve the intended form.
Often, wrought iron is characterized by fibrous appearance but it is also softer, more ductile as opposed to cast iron. It is highly malleable, which means wrought iron can be heated, reheated, and worked into different shapes, and turns stronger the more it is worked.
With regards to how it is used, it has a higher tensile strength as compared to cast iron and that makes it relatively more suitable for a horizontal beam in construction.