Cast Iron Vs Steel: Key Differences Between Explained
Metals such as iron and steel are used by many manufacturers because of their qualities such as strength, durability and ability to keep glossiness for a long time.
Cast iron cookware is a practical example of cast iron’s application, known for its popularity, versatility, and durability. It is widely used for various cooking tasks such as searing steaks and baking cornbread.
However, while metals like cast iron and steel have a similar appearance, they are not the same. This means that both have distinctive features that can be either an advantage or a disadvantage to the production process.
Do you want to know the differences between cast iron vs. steel? Is steel stronger than iron? Read on as we provide answers to these questions and the advantages and disadvantages of these two metals.
Cast Iron and Steel are forms of alloy containing Iron and Carbon. An alloy is a pure mixture of metals or a mixture of metals and other elements. Cast Iron and steel have proven industrial value and hence are used as common construction materials. However, they differ in their composition.
What Is Cast Iron?
Cast iron is an alloy of Iron containing iron as its main metal together with a Carbon percentage which is greater than 2%. Generally, the amount of carbon present varies from 2-4%. Silicon is also found to be another alloying element in Cast Iron with a rough percentage around 1-3% by weight. The presence of these different elements affects the color and the quality of the Cast Iron produced. Certain other impurities such as phosphorus and sulfur can also influence the initiation of cracks in the metal.
Grey cast iron, known for its graphite flakes, has been historically used in various applications due to its good machinability and vibration damping properties.
Cast Iron has a lower melting point than the Iron element. This is because Iron contains other material as impurities. Therefore, it is easy to be casted into molds. Casting is a manufacturing technique where the liquid material is poured into molds and left to solidify. The solidified material is called the ‘casting’ and, once the solidifying is complete, the material can be removed from the mold. Cast Iron is a brittle material which is often cheap. It also has higher heat tolerance level with a high thermal capacity. However, the electric and thermal conductivity is relatively low.
Ductile cast iron, with its spherical graphite nodules, offers higher strength and better toughness compared to grey cast iron, making it suitable for more demanding applications.
Pros Of Cast Iron
- Good casting ability
- Available in large quantities, making production relatively inexpensive.
- It has high compressive strength
- Cast irons have good mechanical ability
- good vibration damping
- low notch sensitivity
- High excellent corrosion resistance
- Low stress concentration
- High resistance to deformation
- High durability
Cons Of Cast Iron
- Prone to corrosion and rust
- Low tensile strength
- High impact resistance
- High weight-to-strength ratio
- High fragility
- Potential issues with enameled cast iron, such as cracking and chipping, and the inability to become nonstick due to the enamel preventing seasoning buildup
What Is Carbon Steel?
Steel is composed of Iron as the main alloying metal with Carbon as the principal second component with a weight percentage around 2.1%. The inclusion of elements such as Chromium makes it possible to produce better quality grades of steel, such as stainless steel. As the name implies stainless steel is resistant to corrosion. This is because Chromium has a higher oxidation potential which in turns protects the Iron from being oxidized upon the exposure to air and moisture.
Steel possess several desirable properties which make it a suitable construction material. Steel has a relatively high viscosity and is difficult to cast as its melting point is higher than cast Iron. It is also milder than cast iron. Unlike cast Iron, steel doesn’t break easily. Instead, it forms chips when grinded and is malleable. Steel has more tensile strength than cast Iron. However, the strength of each material differs on the context of usage. Steel is mainly used for construction, for beams and also for the production of utensils.
Cast carbon steel, with variations in carbon content ranging from low carbon cast steel to mid and high carbon cast steel, impacts the strength and hardness of the material. Higher carbon content generally increases strength and hardness, making cast carbon steel suitable for heavy machinery applications.
Pros Of Steel
High flexibility in design, as you can choose which alloy element you want to combine with the steel
High strength
Corrosion resistance
Easy processing
Cons Of Steel
Steel is more expensive than cast iron
Steel has Less impact resistance
So, between cast iron vs steel, which do you prefer? Having seen the advantages and disadvantages of both types of materials, the material you ultimately choose to use will depend on the requirements of your product.
What Are The Differences Bewteen Cast Iron and Steel?
It can be said that the main difference between steel and cast iron is that steel is produced from iron ore and from metal ore (i.e. scrap) and is called an alloy of iron, with the presence of carbon dominating it, while gray cast iron is the most widely used type of cast iron and is produced on a large scale. So that it produces more than 80% of the total cast iron production, and it consists mainly of carbon (flaky graphite) with a gray color, and provides a low melting point (1145-1250 ℃) and small shrinkage during hardening, approaching carbon steel in terms of strength and hardness, It is able to absorb shocks well.
Cast iron and steel are forms of alloys that contain iron and carbon, and alloys are a pure mixture of metals or a mixture of metals and other elements, and solid iron is an alloy of iron that contains a specific amount Of carbon, cast iron is a hard gray metal that is manufactured with an indefinite amount of carbon. Experience and studies have proven that cast iron and steel have industrial value, and therefore they are used in various building materials. Other differences between steel and cast iron can be explained as follows:
Carbon Content
Iron and steel are both ferrous metals comprised primarily of iron atoms. In manufacturing, however, it’s not that simple—there are many different alloys and grades used in production. To understand them, it’s important to distinguish between the iron used in everyday products, and the scientific element iron (Fe). The elemental iron is the stuff that’s found in nature, typically in an oxidized form that requires intensive processing called smelting to extract.
Pure elemental iron is too soft to be useful in most applications. It gets harder, and therefore more useful, when it’s alloyed, or mixed, with carbon. In fact, carbon composition is the main distinction between cast iron and steel. Cast iron typically contains more than 2 percent carbon, while cast steel often contains between 0.1–0.5 percent carbon.
Carbon steel pans, which are made from cast steel, offer several benefits compared to cast iron. They are easier to maintain, provide even heating, and are highly versatile for various cooking tasks.
Melting Point
Cast iron has a low melting point, which makes it susceptible to rotting in any shape because it does not shrink when it gets cold so it may mold easily. If we should mention here that carbonates and other minerals such as chromium are added to the iron to make alloys and different properties or grades of steel. Like steel, cast iron can be said to be cheaper than steel, and has a low melting point with the ability to mold easily.
Strength
The strength difference between cast iron and steel is a controversial topic. Some people believe that steel is stronger than cast iron and others believe that cast iron and steel are in the same degree of strength, but in fact, cast iron has more compressive strength, while steel is stronger. When comparing steel with cast iron, steel has higher tensile strength and does not rust, as steel is moderate in strength but is harder than cast iron.
Malleable cast iron, known for its uniform organizational properties, resistance to wear and tear, and excellent plasticity and toughness, offers a unique balance of strength and durability.
Hardness
Cast Iron is harder than steel. Steel is stronger than Cast Iron. Steel is tougher than cast iron. Cast iron is brittle. When you hit it, if you hit it hard enough, it shatters. Steel isn’t like that; it’s “softer” than that. When you hit it, you can hit it as hard as you want and it will just bend and thin out some.
Yes, that might mean it will break too, but doing so you must hit it much harder that you would cast iron. It generally takes a shearing action to sever steel (or a brisant explosion); steel is tough. It won’t hold its original shape, but it will hang on and not part.
Machinability
Cast iron is typically much easier to machine than steel. The graphite structure in cast iron breaks away more easily, and in a more uniform manner. Harder irons, such as white iron, are much more difficult to machine due to their brittleness.
Steel isn’t as easy to cut with the same consistency, and it causes more tool wear, resulting in higher production costs. Hardened steels, or those with higher carbon content, also increase tool wear. Softer steel isn’t necessarily any better, however—low-carbon steels, despite being softer, can get gummy and difficult to work with.
Corrosion Resistance
cast iron resists corrosion better than steel. However, these metal materials are not susceptible to corrosion. If you leave them exposed and unprotected, both materials will undergo oxidation, which would lead to decomposition.
Impact Resistance
Steel is better than cast iron at withstanding sudden impacts without bending, deforming, or breaking. This is due to its toughness: its ability to withstand high stress and strain forces.
Cost
Cast iron is cheaper than cast steel because of the lower material costs
Applications
Cast iron is ideal for making pipe fittings, washers, farm equipment, machine parts, mining hardware, electrical fittings, and hand tools. Ductile iron, known for its toughness and strength, is also widely used in applications requiring high durability and resilience, such as automotive components and heavy-duty machinery.
On the other hand, steel is perfect for making tools, weapons, electrical appliances, vehicles, and infrastructure. Malleable iron, recognized for its hardness and wear resistance, is commonly used in applications like brackets, levers, and other components where sound characteristics and durability are essential.
Cast Iron Vs Steel: How to Choose Them For Your Project?
Selecting any of the two types of steel should only occur after understanding the properties of the project. Is cast iron stronger than steel? How is steel made from iron?
Pure iron, unlike cast iron, has a higher carbon content which makes it more brittle and gives it a rough texture and poor heat conductivity. Cast iron is actually an alloy of iron and carbon, which differentiates it from pure iron and steel.
Author
Gavin Leo is a technical writer at Aria with 8 years of experience in Engineering, He proficient in machining characteristics and surface finish process of various materials. and participated in the development of more than 100complex injection molding and CNC machining projects. He is passionate about sharing his knowledge and experience.