The maximum reduction in cross-sectional area per pass ( R ) of a cold wire drawing

Q. The maximum reduction in cross-sectional area per pass ( R ) of a cold wire drawing process is

R = 1 – e-(n+1) ,

where n represents the strain hardening coefficient. For the case of a perfectly plastic material, R is

(A) 0.865                    (B) 0.826                    (C) 0.777                   (D) 0.632

Ans: 0.632