Both Cast iron and Cast steel are ferrous products containing iron and carbon as the major components. Cast iron is a ferrous material containing more than 2% carbon. On the other hand, Cast steel contains less than 2% carbon. So composition-wise the main difference is the amount of carbon present in cast iron and steel. Both cast iron and steel provide very good casting properties and therefore used for a wide range of applications. Both cast iron and cast steel have very good mechanical properties. In this article we will explore the major differences between cast iron and cast steel; i.e Cast iron vs Cast steel.
Cast Iron vs Cast Steel
The main differences between cast iron and cast steel or Cast iron vs Cast Steel is provided below in a tabular format.
|Cast Iron||Cast Steel|
|Cast Iron is very easy to cast due to its very good flowability and low shrinkage.||Cast Steel has less flowability and more shrinkage as compared to Cast Iron.|
|Cast iron is better in terms of corrosion resistance and resistance to mechanical wear.||Cast steel is better in terms of impact loads.|
|Cast iron is cheaper.||Cast Steel is costlier as compared to cast iron.|
|Cast iron have very good vibration damping properties.||In terms of vibration damping, cast steel is inferrior to cast iron.|
|More of Brittle Nature.||Ductile nature.|
|Machinability lower.||Good machinability.|
|Weldability is lower as compared to cast steel||Good Weldability|
|Low melting point||Cast Steel possesses higher melting points.|
|The main element in Cast iron in Iron and Carbon. Other elements can be present of a negligible amount.||Other alloying elements are present in cast steel in considerable amount.|
Cast Iron vs Cast Steel: Which one to Select?
Even though cast iron and cast steel have their own advantages and disadvantages; the selection between cast iron vs cast steel completely depends on end use and application of the product.
Choosing Cast Iron:
- If mechanical strength is of less importance then cast iron is a great choice.
- Select cast iron if heat retention is required as cast iron has higher thermal capacities.
- If the more compressive strength is required, go for cast iron.
- If you need an economic item then choose cast iron as grey iron is cheaper to produce.
- The use of Cast iron is normally limited to low temperature and pressure applications.
Choosing Cast Steel:
- If ductile behavior along with good strength is the requirement then choose Cast Steel.
- If the end product is to be used in impact loading conditions use Cast Steel as it has higher toughness properties.
- If you need very good thermal and electrical conductivity, select cast steel.
- Choose Cast Steel of flexibility in design.
- Use Cast Steel for high temperature and pressure applications.
Cast Iron vs Cast Steel: How to Identify
There are various methods for identification of Cast iron vs Cast Steel. Few methods are listed below:
Chemical Analysis: This is the best method to determine if a specimen is Cast iron or Cast Steel.
Spark Test: One of the easier methods to check cast iron vs cast steel is by spark test. The specimen can be grinded using an abrasive wheel and looking at the spark pattern and spark color, an experienced person can inform if the material is Cast iron or cast steel. Steel will most often give off bright yellow sparks, whereas iron produces more of red or orange sparks.
In cast iron, the spark color tends to be the brightest at the end of the spark whereas for cast steel the spark originates at the grinding wheel and extends outwards as shown in the following image:
Drilling Test: Drilling cast iron vs cast steel looks completely different as can be seen from Fig. 2. In cast iron, the generated chips are of very short length and resemble graphite flakes. On the other hand, the chips of cast steel forms wire like chips.
Grain Structure: Cast iron vs cast steel can also be identified by looking at the grain structures of broken parts. The grain structure for cast iron and cast steel are completely different as can be seen in Fig. 3.