Coarse pearlite refers to pearlite with relatively thick lamellae. Which option correctly describes this?

• A. Pearlite with very thin lamellae.
• B. Pearlite with a random distribution of cementite.
• C. Pearlite for which the alternating ferrite and cementite layers are relatively thick.
• D. A bainitic structure.

Answer: (C)

Coarse pearlite is characterized by the spacing of its lamellae—the alternating ferrite and cementite layers formed during the eutectoid transformation. When cooling is slower, carbon diffusion allows the ferrite and cementite layers to grow longer, making the lamellae thicker. So, describing pearlite where the ferrite and cementite layers are relatively thick captures what “coarse” means in this microstructure. The other descriptions point to distinct scenarios: very thin lamellae describe fine pearlite, a random distribution of cementite isn’t true pearlite’s lamellar structure, and a bainitic structure is a different transformation product altogether.