Cast Iron vs Cast Steel: How to identify Cast Iron vs Cast Steel

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. Both cast iron and cast 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 IronCast 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 steelGood Weldability
Low melting pointCast 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.
Table: Cast Iron vs Cast Steel

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:

Cast Iron vs Cast Steel
Fig. 1: Spark Test: Cast Iron vs Cast Steel

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.

Cast iron vs Cast Steel- Drilling Test
Fig. 2: Cast iron vs Cast Steel- Drilling Test

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.

Cast Iron vs Cast Steel- Grain Structure Test
Fig. 3: Cast Iron vs Cast Steel- Grain Structure Test
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Anup Kumar Dey

I am a Mechanical Engineer turned into a Piping Engineer. Currently, I work in a reputed MNC as a Senior Piping Stress Engineer. I am very much passionate about blogging and always tried to do unique things. This website is my first venture into the world of blogging with the aim of connecting with other piping engineers around the world.

4 thoughts on “Cast Iron vs Cast Steel: How to identify Cast Iron vs Cast Steel

  1. Thank You Mr. Anup,
    Very useful information shared by you for industrial piping engineers or maintenance person.

    I request you to share an idea or demo how to manage piping spares for different standards, as we know numbers od Sizes, types , material and standards are there for a single item, for example an elbow fitting- Socket Weld,Butt Weld, Long Radius-Short Radius, 90-45-60, Material Grade-St35,St37,St52,SS304etc. If I need to keep a record for elbow in a single excel sheet for ease of identification when required how can it be? If you have and idea on it please share with a demo format in excel.

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