Whether you are a business owner or consumer, you are likely to be familiar with cast iron. From cast iron cookware to electrical fittings, pipes, machine parts for auto industry, cast iron has found its place across diverse sectors. But the question is – is cast iron safe? Is it healthy? What are the advantages and disadvantages of cast iron? Which is better – iron or cast iron or steel? We’ll get answers to frequently asked questions about cast iron – its different types, uses, properties and what makes cast iron a popular choice for consumers and business owners.

What is cast iron?

Let’s start with the basics of cast iron meaning – What is cast iron?

Made out of pig iron, cast iron is an iron alloy. It contains iron, small portions of carbon (2% – 4%), and silicon (1% – 3%). It also contains small portions of manganese, sulphur and phosphorous.

Cast iron is strong (i.e., high compressive strength), brittle, and has high heat retention capabilities. It does not wear easily and is highly durable. It is also corrosion resistant.

There are different types of cast iron in the market, the 4 most common types being – Gray cast iron, Ductile cast iron, White cast iron, and Malleable cast iron.

Is cast iron 100% iron?

A common question is – Is cast iron pure iron? Or, is cast iron 100% iron?

Pure iron is a soft metal and often not suitable for use in its actual form for different applications. Cast iron, which is strong, is an alloy of iron made by melting pig iron. Other alloying elements, mainly carbon (2% – 4%) and silicon (1% – 3%) are added to it, to give it its unique characteristics.

As such, nearly 96% -97% of cast iron contains iron. This quantity however varies depending on the grade and type of cast iron in question.

Also read: Iron vs Steel

What is the chemical composition of cast iron?

Now that we understand cast iron meaning, let us take a look at cast iron chemical composition.

We know that cast iron contains iron, carbon, silicon and in parts manganese, sulphur and phosphorous (impurities).

Cast iron composition percentage

Based on the type of cast iron, other elements like chromium, nickel and copper might also be present. These elements enhance the properties of cast iron such as corrosion resistance, strength and ductility.

Now that we understand the chemical composition of cast iron, let’s see how they enhance the unique traits of the alloy.

Also read: Mechanical properties of steel

What are the main properties of cast iron?

Cast iron is versatile and durable. Its chemical and mechanical properties make it unique and suitable for use across a wide range of applications. Let’s take a look at the properties of cast iron.

Cast iron properties

• Strength and durability: Cast iron is robust, strong and durable. It can withstand wear, pressure and damage, making it suitable for manufacturing heavy-duty applications. It has high compressive strength (as against tensile strength) that makes it reliable for use in building and construction projects.
• Brittleness: Cast iron is strong, but the presence of carbon also makes it brittle. It’s not easily bendable and will break under high stress. This makes it necessary to take precautions during its production, especially during cast iron cookware manufacturing process.
• Resistance to corrosion: Like steel, cast iron also demonstrates reasonable resistance to corrosion and can be used in outdoor setups in harsh environments. However, it requires periodic maintenance to prevent rust formation. When used in utensils, regular cleaning and seasoning is recommended.
• Heat retention: Cast iron can retain heat for long duration of time. It also distributes heat evenly making it a preferred component for use in cooking utensils (i.e., cast iron skillets, woks, pots, pans). It’s also used in radiators and heat distributor systems.
• Wear resistance: The presence of small traces of manganese makes cast iron resistant to abrasion and wear. It does not degrade easily making it suitable for use in gears and machinery components. This naturally extends the longevity of the product.
• Castability: It is easy to cast into intricate shapes and sizes. This is true when used for making auto components and machinery, as the liquid, molten material can easily be poured into molds and takes the desired shape.
• Recyclability: Steel recycling is common, which makes it one of the most popular metals. However, cast iron is also easily recyclable, making it sustainable in the long run. This has a positive environmental impact, especially when dealing with production (energy consumption) and disposal.

Also read: Steel scrap recycling policy in India

What are the uses of cast iron?

We now take a look at the diverse applications of cast iron to understand how its distinct characteristics cater to different applications and project needs.

• Manufacturing cookware: Cast iron is most widely used in the manufacturing of cookware and utensils. It’s a staple in many Indian homes for cooking due to its heat retention and ability to withstand high temperatures.
• Machinery and tools: Cast iron, due to its hardness and resistance to wear and deformation, is often used to make heavy machinery and tools. From textile manufacturing to agriculture, cast iron in used to make critical machine parts.
• Automotive components: Though steel in automotive is a staple, cast iron is also used extensively to manufacture engine blocks and cylinder heads. It can absorb vibrations enables smooth, quiet vehicle operations.
• Art and décor: Cast iron is easy to cast and can mold into intricate shapes and varied sizes. This makes it suitable for artistic and decorative items such as benches, fence posts and even statues. Moreover, since it is moderately corrosion resistant and highly durable, it can be used in both indoor and outdoor installations.
• Construction and infrastructure: Cast iron has high compressive strength that makes it suitable for infrastructure development applications. It can commonly be seen used in electrical fittings, pipes, lamp posts, bridges, etc. It can also bear heavy loads which further makes it indispensable.

Also read: Difference between iron and cast iron

Cast iron vs stainless steel vs carbon steel – Which is better?

Now that you understand cast iron meaning, its properties and uses, let’s see how it compares to other alloys – namely steel.

Listed below are some of the common differences between cast iron and stainless steel and carbon steel.

Difference between Cast iron and Stainless steel and Carbon Steel

As such, whether you use cast iron, stainless steel or carbon steel, the application and project requirements will determine which to use. For instance, stainless steel is commonly used for making utensils and surgical devices and stainless steel roofing sheets. Carbon steel on the other hand is used to make rails, railway wheels, and rail axels, steel wire products and gears.

Also read: Carbon steel vs Stainless steel – Which is better and why?

What are the advantages and disadvantages of cast iron?

We’ve discussed the cast iron meaning, the properties and types of cast iron, the main differences between cast iron and steel. We’ll now understand cast iron’s merits and demerits.

Benefits of cast iron:

• Durable: It is durable, strong and can resist wear. It can withstand high temperatures and heavy use making it suitable for industrial applications and cookware.
• Retains heat: Cast iron takes time to heat but can evenly distribute and retain heat for longer duration. This makes it ideal for cookware and utensils.
• Cost-effective: Compared to stainless steel, cast iron is relatively less expensive and suits the budget-conscious consumer.

Disadvantages of cast iron:

• Weight heavy: Cast iron is heavy. This can make it challenging to work with especially for lifting, cleaning and storage.
• Rust prone: Rust can collect over cast iron if not maintained. For instance, with cast iron cookware, periodic cleaning and seasoning with oil is required to remove rust and enhance its performance.
• Brittle: Though cast iron is strong, it is also brittle and can crack if dropped. This limits its application especially where there’s scope of frequent impact with other materials.

Is cast iron good for health?

We’ll close our discussion on cast iron meaning with a vital question – Is cast iron good for health?

This basically refers to using cast iron cookware and whether or not it is safe and healthy to use it everyday.

Cast iron utensils are very popular in Indian cooking. It should however not be used for some basic tasks such as boiling water or cooking food with acidic components (e.g., tomatoes) etc. as it can leave a metallic taste. A minor quantity of iron is usually released when cooking in cast iron skillets, pots and pans. As such, the food cooked in cast iron cookware will have additional iron content. However, this content is absolutely minimum and is also present in other vegetables, legumes, and food items.

It’s therefore recommended that you consult with a medical practitioner first to understand your body’s iron requirements, before using cast iron cookware.

Author: Sohini Banerjee

Sohini is a seasoned content writer with 12 years’ experience in developing marketing and business content across multiple formats. At Tata nexarc, she leverages her skills in crafting curated content on the Indian MSME sector, steel procurement, and logistics. In her personal time, she enjoys reading fiction and being up-to-date on trends in digital marketing and the Indian business ecosystem.