Cast Steel vs Cast Iron - Difference Between Cast Steel and Cast Iron

Although they are both iron-carbon alloys, due to the different percentages of chemical elements such as carbon, silicon, manganese, phosphorus, and sulfur, they have different metallographic structures after crystallization, showing many differences in mechanical properties and process properties.

For example, in the casting state, the elongation, reduction of area, and impact toughness of cast iron are lower than those of cast steel. The compressive strength and shock absorption of cast iron are better than that of cast steel; Gray cast iron has better liquid fluidity than cast steel, and is more suitable for casting thin-walled castings with complex structure; In the bending test, cast iron is a brittle fracture and cast steel is bending deformation. Therefore, they are suitable for casting parts with different requirements.

How to tell the difference between cast iron and cast steel in actual production and life:

1. Brightness. Cast steel is bright. Cast iron is dark and gray. The gray iron in cast iron is different from nodular iron. Nodular iron is brighter than gray iron.

2. Particles. Cast steel is very dense, and particles are generally invisible to the naked eye. Particles can be seen in both gray iron and nodular iron, and the gray iron particles are larger.

3. Sound. The sound of cast steel collision is different from the sound of iron castings.

4. Toughness. The toughness of cast steel is close to that of steel plate, the toughness of nodular cast iron is slightly inferior, the bending of thin-walled parts can reach 20-30 degrees, and the gray cast iron has no toughness. 

5. Others. The surface of steel castings is rough and the area of risers and gates is large, which must be removed by gas cutting. Gas cutting of nodular cast iron can’t be eliminated.

Ductile iron has greater strength and ductility than gray iron. Those properties allow it to be used effectively in a wide variety of industrial applications, including pipe, automotive components, wheels, gear boxes, pump housings, machine frames for the wind-power industry, and many more.