In a spark test, how can cast iron be distinguished from low carbon steel?

In a spark test, the distinguishing feature of low carbon steel compared to cast iron is the nature of the sparks produced when a metal is ground against a grindstone. Low carbon steel emits short, bright sparks with red bursts, which is indicative of its iron content and carbon composition. This characteristic spark pattern occurs because low carbon steel has a higher ductility, allowing it to produce more vigorous sparks that are both bright and short in duration.

Cast iron, on the other hand, has a higher carbon content and a more brittle structure, causing it to produce a different spark pattern that does not feature these short, bright bursts. Instead, cast iron typically yields more sparse and longer sparks.

This testing technique is valuable in metal identification processes in the plumbing and metalworking industries, aiding professionals in determining material types based on their physical and spark-producing properties.