Cast iron possessing which one of the following metallographic structures is best suited fordamping.

Cast iron possessing which one of the following metallographic structures is best suited fordamping capacity in engineering applications?(A) Excess cementite (B) Carbon in temper form(C) Silicon carbide in flake structure (D) Spheroidal form of graphiteIn an orthogonal turning process, the chip thickness = 0.32 mm, feed = 0.2mm/rev. Then thecutting ratio will be