In open-die forging, a disc of diameter 200 mm and height

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In open-die forging, a disc of diameter 200 mm and height 60 mm is compressed without any barreling effect. The final diameter of the disc is 400 mm. The true strain is

1. 1.986
2. 1.686
3. 1.386
4. 0.602

Correct Option: C

π	D²_ih₁ =	π	D²₂h₂
4		4

(200)² × 60 = 400² × 4₂.
Change is length = 45 mm

True stain = ln		h₁		= In		60		= In 4
		h₂				15

True strain 1.386