Question

Which of the following types of cast iron includes black flakes of graphite in it?

(a) White cast iron

(b) Grey cast iron

(c) Ductile cast iron

(d) Malleable cast iron

I had been asked this question in homework.

My enquiry is from Cast Irons in division Foundry Introduction & Materials of Casting-Forming-Welding II

Answer 1

Correct choice is (b) Grey cast iron

Easy explanation: Grey cast iron generally includes thin and little black flakes of graphite. These black flakes cause cast iron to appear in grey color, so it is called as grey cast iron. Presence of graphite can make it use as a lubricant in some manufacturing processes. But it has less tensile strength and toughness than the other cast irons.