Iron is one of the most alloyed elements on earth. It combines with various elements to form numerous materials. These materials all have different desirable properties. Iron is so versatile that its alloys can also combine with other elements to form thousands of new materials. Two well-known types of iron are wrought iron and cast iron. In this article, we will be analysing and comparing wrought iron vs cast iron. We shall discuss their distinct properties, advantages, disadvantages and applications.
Wrought iron is an alloy of iron which contains very minute amounts of carbon (less than 0.08%). It is almost pure iron. It can also be described as iron that has been heated and worked upon with tools. The word “wrought” itself, is a past participle of work. Wrought iron is highly refined iron with small amounts of added slag.
Wrought iron properties
The properties of wrought iron are as follows:
- It is very malleable and weldable. This allows you to reheat and work it into different shapes.
- As a result of its very low carbon content, wrought iron is ductile. It is also relatively light when comparing wrought iron vs cast iron.
- It is resistant to fatigue. When subjected to a large amount of load, it would deform before failing.
- It has a high tensile strength.
- It melts at a high temperature of 1540°C.
Wrought iron and steel have a few similar properties. One of the reasons for this is their similarly low carbon content. People often ask questions like: can wrought iron rust? Or is wrought iron stronger than steel?
First of all, rust is the oxidation of iron. Wrought iron is 99% iron, therefore, it rusts. As for strength, the higher carbon content of steel make it stronger, harder, and less malleable than wrought iron.
Applications of wrought iron
With the advent of cheaper and better alternatives such as steel, wrought iron finds fewer applications in metallurgy. The following are some of its applications:
- You can use it to fabricate creative works such as gates and railings.
- It is used to produce handrails.
- Wrought iron is employed in the production of bolts and nuts.
- It can be used to produce chains.
Cast iron refers to alloys of iron and carbon which contain carbon content of 2 – 4%. You can remelt, pour into a mould and allow this alloy to solidify. Hence the name, “cast” iron. Melting pig iron or smelting iron ore and mixing it with other alloys or scrap metal forms cast iron.
It might interest you to know that there are four types of cast iron which differ in their basic properties. What are the four types of cast iron? They are:
- White cast iron: This contains carbides which result in good wear resistance, high compression strength, and hardness.
- Grey cast iron: This contains graphite in its microstructure. It is easy to machine and is resistant to wear.
- Ductile cast iron: This is a form of grey iron which contains small amounts of caesium and magnesium. These elements nodulate the graphite in grey iron, thereby resulting in high strength and ductility.
- Malleable cast iron: When white cast iron undergoes heat treatment to improve its ductility, it forms malleable cast iron.
Cast iron properties
Cast iron generally has some distinct properties. These properties which are as a result of its mixed micro-structure are as follows:
- It is brittle and relatively heavy.
- When comparing wrought iron vs cast iron, wrought iron has a relatively low melting point (1150 to 1200°C).
- It has excellent fluidity, cast-ability and machinability.
- It is resistant to wear and deformation.
- Although its tensile strength is low, the compression strength of cast iron is very high
Applications of cast iron
Now that we’ve discussed its properties, the next question is, what is cast iron used for? The following are some of the applications of cast iron:
- The Automotive industry use it to produce automobile parts such as cylinder heads, engine blocks, gears, camshafts, etc.
- It is used to fabricate kitchen utensils that come in contact with heat.
- You can also use it for piping applications.
Wrought iron vs cast iron: A comparative analysis
The following are some major differences between wrought iron and cast iron:
- Wrought iron has high tensile strength and is resistant to tensile loading. Cast iron has a relatively low tensile strength but is excellent under compression.
- Cast iron is brittle and hard. Wrought iron is ductile and relatively soft.
- Wrought iron has a high melting point compared to cast iron.
- Cast iron is desirable for its machinability and cast-ability, while wrought iron is desirable for its malleability and weldability.
- Cast iron has greater carbon content than wrought iron.
- Wrought iron is iron that you can heat and work upon. Cast iron is iron that you can remelt and cast.