Difference between Cast Iron and Steel – Which Is Better?
There is a generally foggy idea about cast iron, and steel and not a lot of people know the differences between them. These metals play a huge part in manufacturing and are used by us on a daily basis as cookware. That is why to give you a better idea about two metals and help you choose better, we have made a comprehensive article on cast iron vs cast steel.
The main difference between cast iron and steel is that cast iron contains around 2 to 4% of carbon content. On the other hand, steel contains less than 2% of carbon content. Additionally, if we talk about both metals from the perspective of quality and strength, mild steel has less quality if compared with cast iron. This list goes on but to understand these differences in a better way, it is necessary to learn more about both materials individually.
- What is Cast Iron?
- What is Cast Steel?
- Cast Iron vs and Steel
- Other Elements to Consider
- The Advantages and Disadvantages of Cast Iron
- The Advantages and Disadvantages of Cast Steel
- Cast Iron vs Cast Steel: Which one to choose?
- Wrapping up
1What is Cast Iron?
Cast iron has been used for construction, toolmaking, and ornamentation for over 1,000 years. It is a pure iron alloyed with more than 2% carbon content, meaning it contains more carbon than steel. Because of its low melting point, cast iron does not provide enough flexibility to be pounded into shape, which is why the ironsmith pours the iron into a mould after the smelting process.
Aside from carbon content, cast iron also contains different polluting influences, such as manganese, phosphorus, and sulphur. With a rough weight percentage of around 1-3%, silicon is also found to be an alloying element in Cast Iron, which makes cast iron improve its casting performance. Having these various elements present in cast iron influences its quality and colour.
Hardness, ductility, toughness, and elasticity are some of the mechanical properties of cast iron. It is also tolerant to high heat treatment with a high thermal capacity. One of the major characteristics of this brittle material is that market-cost cast iron is often cheap. However, these mechanical properties change depending on the casting production process. There are various types of cast iron with different production processes. These types include:
- White Cast Iron
- Grey Iron Ore
- Ductile Iron
- Malleable Iron
- Compacted Graphite Iron
In grey iron, the carbon is in the form of sharp free graphite flakes, whereas in ductile iron, the graphite has more spheroidal particles. Flaked graphite structure makes grey iron brittle.
2What is Cast Steel?
In today’s world, steel is very much in demand because of its high-quality performance. It is composed of the impurities that have been removed from iron itself. In this way, steel is just an alloy of iron. Steel has a carbon percentage of less than 2%. It is majorly used for cookware, construction, beams, etc.
Additionally, carbon steel contains elements such as Chromium. Upon exposure to moisture and air, chromium protects iron from oxidation due to its higher oxidation potential. Because of this, producing higher-quality steel grades is made possible. Stainless steel is one of the best quality alloy steel, and it also offers corrosion resistance.
There is a number of desirable properties that make steel a suitable construction material. Steel can be melted into any shape because of its high melting point, and when it cools down, it doesn’t shrink. Additionally, steel also has a relatively high viscosity and it is more difficult to cast. Unlike cast iron, cast steel doesn’t break easily, but it rusts effectively and quickly if compared with cast iron.
3Cast Iron vs and Steel
After learning about cast iron and cast steel in a deeper way, here we have compared some general characteristics of both metals.
|Cast iron has more than 2% of carbon.||Steel has less than 2% of carbon.|
|Cast iron is a hard grey metal.||Steel is an alloy of iron.|
|Cast iron is hard and tough.||Steel is flexible and can be moulded into shapes.|
|Cast iron has a higher compressive strength.||Steel has higher tensile strength.|
|Cast iron has better corrosion resistance.||Steel has less corrosion resistance.|
|Cast iron has a lower cost and is cheaper than steel||Steel is more expensive.|
4Other Elements to Consider
We have also listed some other factors to consider while comparing cast iron vs cast steel. Let’s take a look.
Cast iron has a compressive strength of 6.3 to 7.1 tons/square inch cm with 1.26-1.57 tons/sq. cm rigidity. While mild steel has a compressive strength of 4.75 to 25.2 tons/sq. cm. with 5.51-11.02 tons/sq.cm rigidity. This study shows that steel is a better choice in regard to extreme rigidity.
The castability cast iron shows that it is simpler to cast than steel. More flowability makes cast iron fluid. However, steel is harder to cast because it is less fluid.
Cast iron has a granular and crystalline structure and tends to be whitish or greyish in colour. On the other hand, steel has a stringy and fibrous structure.
With high temperature tolerance, cast iron is extremely hard and tough. Whereas steel can be solidified and pounded using different melting processes. The corrosion resistance of both metal parts also depends upon this.
Made with raw, earthy graphite flakes and often found on meteorites, cast iron breaks easily can it cracks to the point of impurities. Steel, on the other hand, once cooled after melting, doesn’t break or shrink.
Cast iron has a lower melting point at 2200 degrees Fahrenheit, whereas carbon steel has a higher melting point at 2500 – 2800 degrees Fahrenheit. This way, raw steel can be
Alloy steels have high ductility, and the malleability of cast steel is more than ductile iron.
5The Advantages and Disadvantages of Cast Iron
Both cast iron and cast steel have their own advantages and disadvantages. Here are some pointers for you.
Advantages of Cast Iron
- Cast iron has good machinability.
- It has high durability and high compressive strength.
- Cast iron is easily available in large quantities, and it has lower material costs.
- It has good anti-vibration properties and good wear resistance.
- It can withstand high loads and high temperatures.
- Ductile cast iron and malleable iron have high ductility and heat resistance.
- Grey cast iron is easy to access.
Disadvantages of Cast Iron
- The tensile strength of cast iron is low.
- Gray cast iron has high brittleness.
- The production cost of White cast iron, ductile iron and malleable iron are costlier.
- The elongation of Gray iron is very low.
6The Advantages and Disadvantages of Cast Steel
Advantages of Cast Steel
- The major advantage of cast steel is its flexibility, because of which it can be mended into various designs.
- It has a higher melting point, so it can be used to make complex shapes.
- Cast steel provides active resistance to corrosion.
- Cast steel has increased strength and does not break easily.
- Alloy steel has a higher tensile strength, and it is more dependable.
- Cast steel is better in terms of impact loads and ductile nature.
Disadvantages of Cast Steel
- Cast steel is more expensive than grey cast iron.
- It is difficult to cast because of its less flowability.
- Cast steel has bad shake-suction and low wear resistance.
7Cast Iron vs Cast Steel: Which one to choose?
We went through the advantages and disadvantages of cast iron and cast steel based on their mechanical properties. Now the question arises between cast iron vs steel, which one should you prefer? Well, this depends upon your product requirements.
Choose cast iron in the case when mechanical strength is of less importance. When you need an economical, budget-friendly product with heat retention, cast iron is the best option as it has higher thermal capacities. Also, if you require high compressive strength, then go for gray iron.
Cast steel, on the other hand, should be selected when you can make use of its ductile properties and when strength is required. You can choose cast steel when you want to make use of its flexibility to utilise it in making complex shapes. Also, cast steel has good electrical conductivity, so that you can use that.
When it comes to cookware, people generally prefer stainless steel cookware to cast iron cookware. This is because cast iron utensils are naturally non-stick and are an amazing alternative to non-stick cooking. So, if you want a non-stick surface, choose cast iron cookware, as stainless steel utensils are not necessarily non-stick. However, cast iron cookware can always invite apprehension as it can break easily. So, you can always select after researching thoroughly, or better yet, invest in both cookware types.
Cast iron and cast steel are both different metals with different mechanical properties. If we put cast iron vs cast steel, we do not find a clear winner because both materials have their own advantages and disadvantages. That is why we hope that this in-depth blog on cast iron vs cast steel helps you choose appropriately. If you have any more doubts, feel free to write to us, we would love to get your feedback.
Is cast iron more expensive than steel?
No. Cast iron is, in fact, a lot cheaper than cast steel. This is because cast iron is easily accessible, and it requires lower material costs, energy and labour to produce the final product. Raw steel is more expensive than cast iron because it is harder to cast.
What are the disadvantages of cast iron?
Cast iron products are heavy, and they are not good at retaining heat. Also, it has a low melting point and, thus, does not provide enough flexibility. Cast iron cookware also cracks easily.
Can cast iron rust?
Cast iron products, with a protective layer of carbonised oil, do not rust easily. Also, such products need a lot of tending. It is not advisable to keep cast iron products in water or high temperature for a long time. This can welcome early rust even if your product is fairly new.
Is it healthy to cook in cast iron?
For many generations, cast iron utensils were used to cook food on daily basis. Cast iron cookware is a healthier and safer alternative to non-stick cookware. However, it is necessary to know that it is advisable not to cook food in such cookware on high heat. Keep the heat on low to medium while cooking. This way, the cookware won’t break and mix brittles with the food.
Does cast iron crack easily?
It is true that cast iron has brittle mechanical properties. But it is also heavy and tough. So, it does not break easily if you take exceptional care of the cast iron things. For extra safety, keep these products away from kids, cook food in cast iron utensils on low to medium heat and do not keep them in water for a long time to soak.